udf: fix signedness issue

sparse generated:
fs/udf/namei.c:896:15: originally declared here
fs/udf/namei.c:1147:41: warning: incorrect type in argument 3 (different signedness)
fs/udf/namei.c:1147:41:    expected int *offset
fs/udf/namei.c:1147:41:    got unsigned int *<noident>
fs/udf/namei.c:1152:78: warning: incorrect type in argument 3 (different signedness)
fs/udf/namei.c:1152:78:    expected int *offset
fs/udf/namei.c:1152:78:    got unsigned int *<noident>
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/udf/namei.c

@@ -1195,7 +1195,7 @@ static int udf_rename(struct inode *old_dir, struct dentry *old_dentry,
 		}
 	}
 	if (S_ISDIR(old_inode->i_mode)) {
-		uint32_t offset = udf_ext0_offset(old_inode);
+		int offset = udf_ext0_offset(old_inode);
 
 		if (new_inode) {
 			retval = -ENOTEMPTY;