scsi: ufs: dump device descriptor info via debugfs

This change adds a debugfs capability to dump Device Descriptor
information, parsed and detailed. It helps developer to get
important information about the UFS device it handles.

Change-Id: Ia149e4c82e33755b235eb6afe52541c8b23a0708
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>