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>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6fea87d..f355c28 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1952,16 +1952,16 @@
 	if ((sbi->s_es->s_feature_ro_compat &
 	     cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))) {
 		/* Use new metadata_csum algorithm */
-		__u16 old_csum;
+		__le16 save_csum;
 		__u32 csum32;
 
-		old_csum = gdp->bg_checksum;
+		save_csum = gdp->bg_checksum;
 		gdp->bg_checksum = 0;
 		csum32 = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&le_group,
 				     sizeof(le_group));
 		csum32 = ext4_chksum(sbi, csum32, (__u8 *)gdp,
 				     sbi->s_desc_size);
-		gdp->bg_checksum = old_csum;
+		gdp->bg_checksum = save_csum;
 
 		crc = csum32 & 0xFFFF;
 		goto out;