fs/exfat: implement errors=remount-ro

fs/exfat: implement errors=remount-ro

This patch implements errors=remount-ro for exfat.

Port of cf4fa60 and 58ec900 on 8996 with minor change for
updated submit_io() interface in kernel 4.9.

Change-Id: Iee791a99216ecf9f710adffa681706e761f97d8f
Signed-off-by: Shiyong Li <a22381@motorola.com>
Reviewed-on: https://gerrit.mot.com/1102176
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Igor Kovalenko <igork@motorola.com>
Submit-Approved: Jira Key
Reviewed-on: https://gerrit.mot.com/1276877
Reviewed-by: Hua Tan <tanhua1@motorola.com>