hw/alpha/dp264.c: Fix memory leak spotted by valgrind

valgrind complains about:
==7055== 58 bytes in 1 blocks are definitely lost in loss record 1,471 of 2,192
==7055==    at 0x4C2845D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==7055==    by 0x24410F: malloc_and_trace (vl.c:2556)
==7055==    by 0x64C770E: g_malloc (in /usr/lib64/libglib-2.0.so.0.3600.3)
==7055==    by 0x64DEFD7: g_strndup (in /usr/lib64/libglib-2.0.so.0.3600.3)
==7055==    by 0x650181A: g_vasprintf (in /usr/lib64/libglib-2.0.so.0.3600.3)
==7055==    by 0x64DF0CC: g_strdup_vprintf (in /usr/lib64/libglib-2.0.so.0.3600.3)
==7055==    by 0x64DF188: g_strdup_printf (in /usr/lib64/libglib-2.0.so.0.3600.3)
==7055==    by 0x242F81: qemu_find_file (vl.c:2121)
==7055==    by 0x217A32: clipper_init (dp264.c:105)
==7055==    by 0x2484DA: main (vl.c:4249)

Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/alpha/dp264.c

@@ -55,7 +55,7 @@ static void clipper_init(MachineState *machine)
     ISABus *isa_bus;
     qemu_irq rtc_irq;
     long size, i;
-    const char *palcode_filename;
+    char *palcode_filename;
     uint64_t palcode_entry, palcode_low, palcode_high;
     uint64_t kernel_entry, kernel_low, kernel_high;
 
@@ -101,8 +101,8 @@ static void clipper_init(MachineState *machine)
     /* Load PALcode.  Given that this is not "real" cpu palcode,
        but one explicitly written for the emulation, we might as
        well load it directly from and ELF image.  */
-    palcode_filename = (bios_name ? bios_name : "palcode-clipper");
-    palcode_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, palcode_filename);
+    palcode_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS,
+                                bios_name ? bios_name : "palcode-clipper");
     if (palcode_filename == NULL) {
         hw_error("no palcode provided\n");
         exit(1);
@@ -114,6 +114,7 @@ static void clipper_init(MachineState *machine)
         hw_error("could not load palcode '%s'\n", palcode_filename);
         exit(1);
     }
+    g_free(palcode_filename);
 
     /* Start all cpus at the PALcode RESET entry point.  */
     for (i = 0; i < smp_cpus; ++i) {