baytrail: SMM support

Initialize SMM on all CPUs by relocating the SMM region
and setting SMRR on all the cores. Additionally SMI
is enabled in the south cluster.

BUG=chrome-os-partner:22862
BRANCH=None
TEST=Built and booted rambi. Tested with DEBUG_SMI and noted
     power button turns off board while in firmware.

Change-Id: I92e3460572feeb67d4a3d4d26af5f0ecaf7d3dd5
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/173983
Reviewed-on: http://review.coreboot.org/4892
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

src/soc/intel/baytrail/memmap.c

@@ -20,8 +20,14 @@
 #include <arch/io.h>
 #include <cbmem.h>
 #include <baytrail/iosf.h>
+#include <baytrail/smm.h>
+
+void *smm_region_start(void)
+{
+	return (void *)(iosf_bunit_read(BUNIT_SMRRL) << 20);
+}
 
 unsigned long get_top_of_ram(void)
 {
-	return (unsigned long)(iosf_bunit_read(BUNIT_SMRRL) << 20);
+	return (unsigned long)smm_region_start();
 }