ANDROID: scsi: ufs: add a hook to prepare command

This patch adds one variant in UFS driver:

void    (*prepare_command)(struct ufs_hba *hba,
                        struct request *rq, struct ufshcd_lrb *lrbp);
 -> called in the beginning of queuecommand to update the request, if needed

Bug: 158050260
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Change-Id: Ib91a735c2cbd215c1854ff57ef9a92642c41e005