arch/x86: Always include walkcbfs.S

Let the linker decide if this code is needed.

Change-Id: I26fb19d461db39ce554af7b948f0d10a12920299
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52940
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/arch/x86/Makefile.inc

@@ -91,7 +91,7 @@ else
 $(eval $(call early_x86_stage,bootblock,elf64-x86-64))
 endif
 
-bootblock-$(CONFIG_MICROCODE_UPDATE_PRE_RAM) += walkcbfs.S
+bootblock-y += walkcbfs.S
 
 endif # CONFIG_ARCH_BOOTBLOCK_X86_32 / CONFIG_ARCH_BOOTBLOCK_X86_64