aspeed: Use the boot_rom region of the fby35 machine

This change completes commits 5aa281d ("aspeed: Introduce a
spi_boot region under the SoC") and 8b744a6 ("aspeed: Add a
boot_rom overlap region in the SoC spi_boot container") which
introduced a spi_boot container at the SoC level to map the boot rom
region as an overlap.

It also fixes a Coverity report (CID 1508061) for a memory leak
warning when the QEMU process exits by using an bmc_boot_rom
MemoryRegion available at the machine level.

Cc: Peter Delevoryas <peter@pjd.dev>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/arm/fby35.c

@@ -70,8 +70,6 @@ static void fby35_bmc_write_boot_rom(DriveInfo *dinfo, MemoryRegion *mr,
 
 static void fby35_bmc_init(Fby35State *s)
 {
-    DriveInfo *drive0 = drive_get(IF_MTD, 0, 0);
-
     object_initialize_child(OBJECT(s), "bmc", &s->bmc, "ast2600-a3");
 
     memory_region_init(&s->bmc_memory, OBJECT(&s->bmc), "bmc-memory",
@@ -95,18 +93,21 @@ static void fby35_bmc_init(Fby35State *s)
     aspeed_board_init_flashes(&s->bmc.fmc, "n25q00", 2, 0);
 
     /* Install first FMC flash content as a boot rom. */
-    if (drive0) {
-        AspeedSMCFlash *fl = &s->bmc.fmc.flashes[0];
-        MemoryRegion *boot_rom = g_new(MemoryRegion, 1);
-        uint64_t size = memory_region_size(&fl->mmio);
-
-        if (!s->mmio_exec) {
-            memory_region_init_rom(boot_rom, NULL, "aspeed.boot_rom",
-                                   size, &error_abort);
-            memory_region_add_subregion(&s->bmc_memory, FBY35_BMC_FIRMWARE_ADDR,
-                                        boot_rom);
-            fby35_bmc_write_boot_rom(drive0, boot_rom, FBY35_BMC_FIRMWARE_ADDR,
-                                     size, &error_abort);
+    if (!s->mmio_exec) {
+        DriveInfo *mtd0 = drive_get(IF_MTD, 0, 0);
+
+        if (mtd0) {
+            AspeedSoCState *bmc = &s->bmc;
+            uint64_t rom_size = memory_region_size(&bmc->spi_boot);
+
+            memory_region_init_rom(&s->bmc_boot_rom, NULL, "aspeed.boot_rom",
+                                   rom_size, &error_abort);
+            memory_region_add_subregion_overlap(&bmc->spi_boot_container, 0,
+                                                &s->bmc_boot_rom, 1);
+
+            fby35_bmc_write_boot_rom(mtd0, &s->bmc_boot_rom,
+                                     FBY35_BMC_FIRMWARE_ADDR,
+                                     rom_size, &error_abort);
         }
     }
 }