fs: fat: use constant DELETED_FLAG

When deleting a directory entry 0xe5 is written to name[0].

We have a constant for this value and should use it consistently.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 56ea285..c403d7d 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -1464,7 +1464,7 @@
 	 *  - find and mark the "new" first invalid entry as name[0]=0x00
 	 */
 	memset(dentptr, 0, sizeof(*dentptr));
-	dentptr->name[0] = 0xe5;
+	dentptr->name[0] = DELETED_FLAG;
 
 	if (flush_dir(itr)) {
 		printf("error: writing directory entry\n");