UBIFS: improve find function interface

Make 'ubifs_find_free_space()' return offset where free space starts,
rather than the amount of free space. This is just more appropriat
for its caller.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 039a68b..2da1193 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1500,7 +1500,7 @@
 long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs);
 
 /* find.c */
-int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
+int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *offs,
 			  int squeeze);
 int ubifs_find_free_leb_for_idx(struct ubifs_info *c);
 int ubifs_find_dirty_leb(struct ubifs_info *c, struct ubifs_lprops *ret_lp,