MMCONF_SUPPORT: Flip default to enabled

Also remove separate MMCONF_SUPPORT_DEFAULT flag.

Change-Id: Idf1accdb93843a8fe2ee9c09fb984968652476e0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/17694
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/northbridge/intel/nehalem/Kconfig

@@ -16,7 +16,6 @@
 config NORTHBRIDGE_INTEL_NEHALEM
 	bool
 	select CPU_INTEL_MODEL_2065X
-	select MMCONF_SUPPORT_DEFAULT
 	select VGA
 	select INTEL_EDID
 	select TSC_MONOTONIC_TIMER