ext4: remove set but rewrite variables

In the ext4_dx_add_entry function, the at variable is assigned but will
reset just after “again:” label. So delete the unnecessary assignment.
this will not chang the logic.
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Link: https://lore.kernel.org/r/1621493752-36890-1-git-send-email-tiantao6@hisilicon.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/namei.c

@@ -2499,7 +2499,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 
 			/* Which index block gets the new entry? */
 			if (at - entries >= icount1) {
-				frame->at = at = at - entries - icount1 + entries2;
+				frame->at = at - entries - icount1 + entries2;
 				frame->entries = entries = entries2;
 				swap(frame->bh, bh2);
 			}