Use actual bit position instead of UFS_BIT() macro. This patch also
changes bit-17 to meaningful #define.

This change is as per discussion here [1]
[1] -> https://lkml.org/lkml/2017/8/28/786Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Subhash Jadavani <subhashj@codeaurora.org>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>