hw/dma/xlnx_csu_dma: Set TYPE_XLNX_CSU_DMA class_size

In commit 00f05c0 we gave the TYPE_XLNX_CSU_DMA object its
own class struct, but forgot to update the TypeInfo::class_size
accordingly.  This meant that not enough memory was allocated for the
class struct, and the initialization of xcdc->read in the class init
function wrote off the end of the memory. Add the missing line.

Found by running 'check-qtest-aarch64' with a clang
address-sanitizer build, which complains:

==2542634==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61000000ab00 at pc 0x559a20aebc29 bp 0x7fff97df74d0 sp 0x7fff97df74c8
WRITE of size 8 at 0x61000000ab00 thread T0
    #0 0x559a20aebc28 in xlnx_csu_dma_class_init /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../hw/dma/xlnx_csu_dma.c:722:16
    #1 0x559a21bf297c in type_initialize /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../qom/object.c:365:9
    #2 0x559a21bf3442 in object_class_foreach_tramp /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../qom/object.c:1070:5
    #3 0x7f09bcb641b7 in g_hash_table_foreach (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x401b7)
    #4 0x559a21bf3c27 in object_class_foreach /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../qom/object.c:1092:5
    #5 0x559a21bf3c27 in object_class_get_list /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../qom/object.c:1149:5
    #6 0x559a2081a2fd in select_machine /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../softmmu/vl.c:1661:24
    #7 0x559a2081a2fd in qemu_create_machine /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../softmmu/vl.c:2146:35
    #8 0x559a2081a2fd in qemu_init /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../softmmu/vl.c:3706:5
    #9 0x559a20720ed5 in main /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../softmmu/main.c:49:5
    #10 0x7f09baec00b2 in __libc_start_main /build/glibc-sMfBJT/glibc-2.31/csu/../csu/libc-start.c:308:16
    #11 0x559a2067673d in _start (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/qemu-system-aarch64+0xf4b73d)

0x61000000ab00 is located 0 bytes to the right of 192-byte region [0x61000000aa40,0x61000000ab00)
allocated by thread T0 here:
    #0 0x559a206eeff2 in calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/qemu-system-aarch64+0xfc3ff2)
    #1 0x7f09bcb7bef0 in g_malloc0 (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x57ef0)
    #2 0x559a21bf3442 in object_class_foreach_tramp /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/san/../../qom/object.c:1070:5

Fixes: 00f05c0 ("hw/dma/xlnx_csu_dma: Support starting a read transfer through a class method")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Francisco Iglesias <francisco.iglesias@xilinx.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220308150207.2546272-1-peter.maydell@linaro.org

hw/dma/xlnx_csu_dma.c

@@ -744,6 +744,7 @@ static const TypeInfo xlnx_csu_dma_info = {
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(XlnxCSUDMA),
     .class_init    = xlnx_csu_dma_class_init,
+    .class_size    = sizeof(XlnxCSUDMAClass),
     .instance_init = xlnx_csu_dma_init,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_STREAM_SINK },