Kconfig: Make stage cache kconfig selection proper

This patch makes stage cache kconfig proper:

1. Create generic stage cache options as external or internal
stage cache for any relocatable stage
- Define kconfig options as below for platform to select
(A) USE_EXTERNAL_STAGE_CACHE
(B) USE_CBMEM_STAGE_CACHE
- Option (A) and (B) are mutually exclusive
2. Modify .inc and .c as applicable with those configs.

Change-Id: I45e894ad335a4661cc7916b3768e1614a038b31c
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
---
M src/Kconfig
M src/cpu/intel/haswell/Makefile.inc
M src/cpu/intel/model_2065x/Kconfig
M src/cpu/intel/model_206ax/Kconfig
M src/cpu/intel/model_206ax/Makefile.inc
M src/cpu/intel/smm/gen1/smmrelocate.c
M src/include/stage_cache.h
M src/lib/Makefile.inc
M src/northbridge/intel/gm45/Kconfig
M src/northbridge/intel/gm45/Makefile.inc
M src/northbridge/intel/haswell/Kconfig
M src/northbridge/intel/i945/Kconfig
M src/northbridge/intel/i945/Makefile.inc
M src/northbridge/intel/pineview/Kconfig
M src/northbridge/intel/pineview/Makefile.inc
M src/northbridge/intel/x4x/Kconfig
M src/northbridge/intel/x4x/Makefile.inc
M src/soc/amd/picasso/Kconfig
M src/soc/amd/stoneyridge/Kconfig
M src/soc/intel/apollolake/Kconfig
M src/soc/intel/braswell/Kconfig
M src/soc/intel/broadwell/Kconfig
M src/soc/intel/cannonlake/Kconfig
M src/soc/intel/icelake/Kconfig
M src/soc/intel/skylake/Kconfig
25 files changed, 62 insertions(+), 44 deletions(-)