ext4: fix miscellaneous big endian warnings

None of these result in any bug, but they makes sparse complain.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/namei.c

@@ -416,15 +416,16 @@ static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
 {
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	struct ext4_inode_info *ei = EXT4_I(inode);
-	__u32 csum, old_csum;
+	__u32 csum;
+	__le32 save_csum;
 	int size;
 
 	size = count_offset + (count * sizeof(struct dx_entry));
-	old_csum = t->dt_checksum;
+	save_csum = t->dt_checksum;
 	t->dt_checksum = 0;
 	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
 	csum = ext4_chksum(sbi, csum, (__u8 *)t, sizeof(struct dx_tail));
-	t->dt_checksum = old_csum;
+	t->dt_checksum = save_csum;
 
 	return cpu_to_le32(csum);
 }