exfat: fix overflow for large capacity partition

Using int type for sector index, there will be overflow in a large
capacity partition.

For example, if storage with sector size of 512 bytes and partition
capacity is larger than 2TB, there will be overflow.

Fixes: 1b613838 ("exfat: reduce block requests when zeroing a cluster")
Cc: stable@vger.kernel.org # v5.19+
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Andy Wu <Andy.Wu@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

fs/exfat/fatent.c

@@ -270,8 +270,7 @@ int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
 	struct super_block *sb = dir->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 	struct buffer_head *bh;
-	sector_t blknr, last_blknr;
-	int i;
+	sector_t blknr, last_blknr, i;
 
 	blknr = exfat_cluster_to_sector(sbi, clu);
 	last_blknr = blknr + sbi->sect_per_clus;