armv7: Clean up the mmu setup a bit

The previous incarnation did not use all of mmu_setup, which meant
we did not carefully disable things before (possibly) changing them.

This code is tested and works, and it's a bit of a simplification.

Change-Id: I0560f9b8e25f31cd90e34304d6ec987fc5c87699
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2204
Reviewed-by: Peter Stuge <peter@stuge.se>
Tested-by: build bot (Jenkins)

src/cpu/samsung/exynos5250/exynos_cache.c

@@ -39,7 +39,8 @@ enum l2_cache_params {
 void enable_caches(void)
 {
 	/* Enable D-cache. I-cache is already enabled in start.S */
-	dcache_enable();
+	/* can't use it anyway -- it has dependencies we have to fix. */
+	//dcache_enable();
 }
 #endif