ufs: adjust queue settings to PRDT limitations

The data byte count field of PRDT indicates the length of data block
which is a segment of data transfer for SCSI commands.  The value of
this field shall have Dword granularity and the the maximum of length
is 256KB.

This adjusts dma pad mask and max segment size to the above-mentioned
PRDT limitations.

Change-Id: I711ea921e8d3cbd95fd122e1b7d38a29f9bc29ef
Signed-off-by: Akinobu Mita <mita@fixstars.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Patch-mainline: linux-scsi@vger.kernel.org @ 2013/09/25, 22:47
Signed-off-by: Dolev Raviv <draviv@codeaurora.org>