cpu/x86: Introduce CPU_X86_CACHE_HELPER

There's no need for relative paths with Kconfig options.

Change-Id: Ib9b9b29a158c34a30480aaabf6d0b23819d28427
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44226
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/cpu/intel/socket_m/Kconfig

@@ -7,6 +7,7 @@ config SOCKET_SPECIFIC_OPTIONS
 	def_bool y
 	select CPU_INTEL_MODEL_6EX
 	select CPU_INTEL_MODEL_6FX
+	select CPU_X86_CACHE_HELPER
 	select MMX
 	select SSE
 

src/cpu/intel/socket_m/Makefile.inc

@@ -1,7 +1,6 @@
 subdirs-y += ../model_6ex
 subdirs-y += ../model_6fx
 subdirs-y += ../../x86/lapic
-subdirs-y += ../../x86/cache
 subdirs-y += ../microcode
 subdirs-y += ../speedstep