md/md-cluster: fix spares warnings for __le64

md/md-cluster: fix spares warnings for __le64

drivers/md/md-cluster.c:1220:22: warning: incorrect type in assignment (different base types)
drivers/md/md-cluster.c:1220:22:    expected unsigned long my_sync_size
drivers/md/md-cluster.c:1220:22:    got restricted __le64 [usertype] sync_size
drivers/md/md-cluster.c:1252:35: warning: incorrect type in assignment (different base types)
drivers/md/md-cluster.c:1252:35:    expected unsigned long sync_size
drivers/md/md-cluster.c:1252:35:    got restricted __le64 [usertype] sync_size
drivers/md/md-cluster.c:1253:41: warning: restricted __le64 degrades to integer

Fix the warnings by using le64_to_cpu() to convet __le64 to integer.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-6-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>