hw/arm/fby35: Map BMC memory into system memory

Add the BMC memory region as a subregion of system_memory so that
modules relying on system memory can operate correctly.

Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250523093144.991408-6-steven_lee@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/arm/fby35.c

@@ -77,6 +77,7 @@ static void fby35_bmc_init(Fby35State *s)
 
     memory_region_init(&s->bmc_memory, OBJECT(&s->bmc), "bmc-memory",
                        UINT64_MAX);
+    memory_region_add_subregion(get_system_memory(), 0, &s->bmc_memory);
     memory_region_init_ram(&s->bmc_dram, OBJECT(&s->bmc), "bmc-dram",
                            FBY35_BMC_RAM_SIZE, &error_abort);