soc/intel/common: Add missing SoC common function into SMM library

Modify SMM common code in order to accommodate SKL, CNL, APL, GLK
SOC code.

Change-Id: Ie9f90df3336c1278b73284815b5197400512c1d2
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/22869
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/cannonlake/cpu.c

@@ -26,6 +26,7 @@
 #include <soc/cpu.h>
 #include <soc/msr.h>
 #include <soc/pci_devs.h>
+#include <soc/pm.h>
 #include <soc/smm.h>
 
 static void soc_fsp_load(void)
@@ -216,7 +217,7 @@ static void post_mp_init(void)
 	 * Now that all APs have been relocated as well as the BSP let SMIs
 	 * start flowing.
 	 */
-	smm_southbridge_enable();
+	smm_southbridge_enable(PWRBTN_EN | GBL_EN);
 
 	/* Lock down the SMRAM space. */
 	smm_lock();