ARM: API to Map Physical Address to Wipe Memory above 4GB

TEST=Booted nyan in normal and recovery mode. Created a map, filled it with some
chars, then verified they can be read from the pointer returned.
BUG=chrome-os-partner:25587
BRANCH=None
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>

Original-Change-Id: Id1f1be4f6d2d5734d87bf3452d4806d0fe3fda88
Original-Reviewed-on: https://chromium-review.googlesource.com/188894
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Original-Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
(cherry picked from commit 7fda3885f51c8d383585a80e99ab3df9c789d872)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I6255d11396c87f40b0ae12ceab0fd152f2478529
Reviewed-on: http://review.coreboot.org/7658
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/payloads/libpayload/include/stddef.h b/payloads/libpayload/include/stddef.h
index f9deaeb..fca66ed 100644
--- a/payloads/libpayload/include/stddef.h
+++ b/payloads/libpayload/include/stddef.h
@@ -15,3 +15,7 @@
 
 #define offsetof(TYPE, MEMBER)	((size_t) &((TYPE *) 0)->MEMBER)
 
+/* Standard units. */
+#define KiB (1<<10)
+#define MiB (1<<20)
+#define GiB (1<<30)