ext4: fix unused iterator variable warnings

When CONFIG_QUOTA is disabled, there are warnings around unused iterator
variables:

  fs/ext4/super.c: In function 'ext4_put_super':
  fs/ext4/super.c:1262:13: error: unused variable 'i' [-Werror=unused-variable]
   1262 |         int i, err;
        |             ^
  fs/ext4/super.c: In function '__ext4_fill_super':
  fs/ext4/super.c:5200:22: error: unused variable 'i' [-Werror=unused-variable]
   5200 |         unsigned int i;
        |                      ^
  cc1: all warnings being treated as errors

The kernel has updated to GNU11, allowing the variables to be declared
within the for loop.  Do so to clear up the warnings.

Fixes: dcbf8758 ("ext4: factor out ext4_flex_groups_free()")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230420-ext4-unused-variables-super-c-v1-1-138b6db6c21c@kernel.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -1259,7 +1259,7 @@ static void ext4_put_super(struct super_block *sb)
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
 	int aborted = 0;
-	int i, err;
+	int err;
 
 	/*
 	 * Unregister sysfs before destroying jbd2 journal.
@@ -1311,7 +1311,7 @@ static void ext4_put_super(struct super_block *sb)
 	ext4_flex_groups_free(sbi);
 	ext4_percpu_param_destroy(sbi);
 #ifdef CONFIG_QUOTA
-	for (i = 0; i < EXT4_MAXQUOTAS; i++)
+	for (int i = 0; i < EXT4_MAXQUOTAS; i++)
 		kfree(get_qf_name(sb, sbi, i));
 #endif
 
@@ -5197,7 +5197,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	ext4_fsblk_t logical_sb_block;
 	struct inode *root;
 	int ret = -ENOMEM;
-	unsigned int i;
 	int needs_recovery;
 	int err = 0;
 	ext4_group_t first_not_zeroed;
@@ -5628,7 +5627,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 #endif
 
 #ifdef CONFIG_QUOTA
-	for (i = 0; i < EXT4_MAXQUOTAS; i++)
+	for (unsigned int i = 0; i < EXT4_MAXQUOTAS; i++)
 		kfree(get_qf_name(sb, sbi, i));
 #endif
 	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);