Intel cpus: apply un-written naming rules

Kconfig directives to select chip drivers for compile literally
match the chip directory names capitalized and underscored.

Note: CPU_INTEL_CORE2 was used on both model_6fx and model_1067x.

Change-Id: I8fa5ba71b14dcce79ab2a2c1c69b3bc36edbdea0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/618
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/intel/model_6ex/Kconfig

@@ -1,4 +1,4 @@
-config CPU_INTEL_CORE
+config CPU_INTEL_MODEL_6EX
 	bool
 	select SMP
 	select SSE2