scsi: ufs: update device descriptor maximum size

According to JESD220B - UFS v2.0, the maximum size of device descriptor
has changed from 0x1F to 0x40. This patch updates the maximum size of
this descriptor.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>