drm/fourcc: Fix undefined left shift in DRM_FORMAT_BIG_ENDIAN macros

1<<31 is undefined because it's a signed int and C is terrible.
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191018175041.613780-1-ajax@redhat.com

include/uapi/drm/drm_fourcc.h

@@ -69,7 +69,7 @@ extern "C" {
 #define fourcc_code(a, b, c, d) ((__u32)(a) | ((__u32)(b) << 8) | \
 				 ((__u32)(c) << 16) | ((__u32)(d) << 24))
 
-#define DRM_FORMAT_BIG_ENDIAN (1<<31) /* format is big endian instead of little endian */
+#define DRM_FORMAT_BIG_ENDIAN (1U<<31) /* format is big endian instead of little endian */
 
 /* Reserve 0 for the invalid format specifier */
 #define DRM_FORMAT_INVALID	0