sgx: Move SGX code to intel/common/block

CONFIG_SOC_INTEL_COMMON_BLOCK_SGX controls building. The SGX feature
is still enabled from devicetree.cb. As of now this SGX init supports
only KBL (SKL not tested). Support of SGX for new SOCs would be added
incrementally in this common code base.

Change-Id: I0fbba364b7342e686a2287ea1a910ef9a4eed595
Signed-off-by: Pratik Prajapati <pratikkumar.v.prajapati@intel.com>
Reviewed-on: https://review.coreboot.org/20173
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/soc/intel/skylake/Kconfig b/src/soc/intel/skylake/Kconfig
index 1dc8055..c558886 100644
--- a/src/soc/intel/skylake/Kconfig
+++ b/src/soc/intel/skylake/Kconfig
@@ -65,6 +65,7 @@
 	select SOC_INTEL_COMMON_BLOCK_SA
 	select SOC_INTEL_COMMON_BLOCK_SATA
 	select SOC_INTEL_COMMON_BLOCK_SCS
+	select SOC_INTEL_COMMON_BLOCK_SGX
 	select SOC_INTEL_COMMON_BLOCK_SMBUS
 	select SOC_INTEL_COMMON_BLOCK_TIMER
 	select SOC_INTEL_COMMON_BLOCK_UART