Porting the sdcard panic fix from qcom

Porting the sdcard panic fix from qcom

Porting the change 226f96b0 from QCOM
Fix potential crash when reserved_mb is not zero
Author: Lianjun Huang <huanglianjun@vivo.com>
sdcardfs_mkdir() calls check_min_free_space(). When
reserved_mb is not zero, a negative dentry will be passed to
ext4_statfs at last and ext4_statfs() will crash. The parent dentry
is possitive. So we use the parrent dentry to check free space.

Change-Id: I0c7c6e38cf116660bc573a7e81a679366aa6c334
Signed-off-by: a17671 <a17671@motorola.com>
Reviewed-on: https://gerrit.mot.com/1242998
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Master Yoda
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key