f2fs: use unlikely for release case

Since the variable release is only nonzero when another unlikely
case occurs, use unlikely() on it seems logical.

Signed-off-by: Fan li <[e-mail]>
Reviewed-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/f2fs.h

···
 	}
 	spin_unlock(&sbi->stat_lock);
 
-	if (release)
+	if (unlikely(release))
 		dquot_release_reservation_block(inode, release);
 	f2fs_i_blocks_write(inode, *count, true, true);
 	return 0;