x86: bayleybay: Adjust VGA rom address

Adjust VGA rom address to 0xfffb0000 so that u-boot.rom image can be
built again.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

configs/bayleybay_defconfig

@@ -5,7 +5,7 @@ CONFIG_TARGET_BAYLEYBAY=y
 CONFIG_INTERNAL_UART=y
 CONFIG_SMP=y
 CONFIG_HAVE_VGA_BIOS=y
-CONFIG_VGA_BIOS_ADDR=0xfffa0000
+CONFIG_VGA_BIOS_ADDR=0xfffb0000
 CONFIG_GENERATE_PIRQ_TABLE=y
 CONFIG_GENERATE_MP_TABLE=y
 CONFIG_GENERATE_ACPI_TABLE=y