ANDROID: scsi: ufs: add a hook to add sysfs entries

This patch adds a variant in UFS driver:

int     (*update_sysfs)(struct ufs_hba *hba);
 -> called after creating sysfs for vendor to add more sysfs entries

Bug: 158050260
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Change-Id: Id8c1197ec704e998e89dc25cc69b0f6a1b86e978