exfat: remove the check for infinite cluster chain loop

exfat: remove the check for infinite cluster chain loop

The infinite cluster chain loop check is not work because the
loop will terminate when fclus reaches the parameter cluster,
and the parameter cluster value is never greater than
ei->valid_size.

The following relationship holds:
'fclus' < 'cluster' ≤ ei->valid_size ≤ sb->num_clusters

The check would only be triggered if a cluster number greater than
sb->num_clusters is passed, but no caller currently does this.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>