x86: provide symmetry between arm for cache_sync_instructions()

The arm architecture currently exports cache_sync_instructions()
in <arch/cache.h>. In order for rmodule loading to work on arm
architectures the cache_sync_instructions() needs to be called to
sequence the instruction cache. To avoid sprinkling #ifdefs around
just add an empty cache_sync_instructions() definition.

BUG=chrome-os-partner:27094
BRANCH=None
TEST=Built and booted nyan and rambi.

Original-Change-Id: I1a969757fffe0ca92754a0d953ba3630810556e3
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/191551
Original-Reviewed-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit fda20947b928ee761d5ed15e414636af419970a6)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I3e8ca12e1d82ccedf1ff9851ae3c5c80cda2dd5f
Reviewed-on: http://review.coreboot.org/7710
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/lib/rmodule.c

@@ -20,6 +20,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <arch/cache.h>
 #include <console/console.h>
 #include <rmodule.h>
 
@@ -196,6 +197,9 @@ int rmodule_load(void *base, struct rmodule *module)
 	if (rmodule_relocate(module))
 		return -1;
 	rmodule_clear_bss(module);
+
+	cache_sync_instructions();
+
 	return 0;
 }