exfat: remove the assignment of 0 to bool variable

There is no need to init 'sync' in exfat_set_vol_flags().
This also fixes the following coccicheck warning:

fs/exfat/super.c:104:6-10: WARNING: Assignment of 0/1 to bool variable

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Git-commit: cdc06129a6cea0e4863fa2b34a0c132c6eb7278b
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: lixiang <lixiang@codeaurora.org>