include: export uuid.h

Move this header to include/u-boot/ so that it can be used by external
tools.

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/common/flash.c b/common/flash.c
index 24ddc8b..226646c 100644
--- a/common/flash.c
+++ b/common/flash.c
@@ -8,7 +8,7 @@
 
 #include <flash.h>
 #include <log.h>
-#include <uuid.h>
+#include <u-boot/uuid.h>
 #include <linux/string.h>
 
 #include <mtd/cfi_flash.h>