struct ufs_dev_cmd is the main container that supports device management
commands. In the case of a read descriptor request, we assume that the
proper space was allocated in dev_cmd to hold the returning descriptor.

This is no longer true, as there are flows that doesn't use dev_cmd for
device management requests, and was wrong in the first place.

Fixes: d44a5f98 (ufs: query descriptor API)
Signed-off-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Acked-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>