fs/exfat: reduce log spam

fs/exfat: reduce log spam

Switch to debug prints for some spammy errors.

Change-Id: I847d21fcaa4a66b0521e43c62fe7d7b6c1e140d7
Signed-off-by: Igor Kovalenko <cik009@motorola.com>
Signed-off-by: Shiyong Li <a22381@motorola.com>
Reviewed-on: https://gerrit.mot.com/1102185
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/1276886
Reviewed-by: Hua Tan <tanhua1@motorola.com>