x86: Compile coreboot_table.c only for SeaBIOS

coreboot_table.c only needs to be built when SeaBIOS is used.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/x86/lib/Makefile

@@ -10,7 +10,7 @@ obj-y += bios_asm.o
 obj-y += bios_interrupts.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
 obj-y	+= cmd_boot.o
-obj-y	+= coreboot_table.o
+obj-$(CONFIG_SEABIOS) += coreboot_table.o
 obj-$(CONFIG_EFI) += efi/
 obj-y	+= e820.o
 obj-y	+= gcc.o