Fix PRIu64 definition to llu.

Previous CL http://codereview.chromium.org/5634003 has a typo.
PRIu64 should be "llu" instead of "ll".

BUG=None
TEST=Build successfully and run with u-boot and verify that outputs with PRI

Change-Id: I960c422ed0446463d5fed5ac4a12f7728ddbb53b

Review URL: http://codereview.chromium.org/5687001
diff --git a/firmware/arch/arm/include/biosincludes.h b/firmware/arch/arm/include/biosincludes.h
index e2a1d65..b7feacb 100644
--- a/firmware/arch/arm/include/biosincludes.h
+++ b/firmware/arch/arm/include/biosincludes.h
@@ -20,7 +20,7 @@
 #endif
 
 #define UINT64_C(x) ((uint64_t) x)
-#define PRIu64 "ll"
+#define PRIu64 "llu"
 extern void debug(const char *format, ...);
 
 #define POSSIBLY_UNUSED __attribute__((unused))
diff --git a/firmware/stub/include/biosincludes.h b/firmware/stub/include/biosincludes.h
index 718361a..bd7e6fd 100644
--- a/firmware/stub/include/biosincludes.h
+++ b/firmware/stub/include/biosincludes.h
@@ -26,7 +26,7 @@
 
 #define UINT64_C(x) ((uint64_t)x)
 #define __attribute__(x)
-#define PRIu64 "ll"
+#define PRIu64 "llu"
 extern void debug(const char *format, ...);
 
 #define POSSIBLY_UNUSED