scsi: ufs: Fix kernel-doc errors and warnings

Avoid that the kernel-doc tool complains about mismatches between
kernel-doc headers and function definitions. Avoid that errors like the
following are reported when building the UFS driver with W=1:

drivers/scsi/ufs/tc-dwc-g210-pci.c:60: error: Cannot parse struct or union!
drivers/scsi/ufs/tc-dwc-g210-pltfrm.c:26: warning: cannot understand function prototype: 'struct ufs_hba_variant_ops tc_dwc_g210_20bit_pltfm_hba_vops = '

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Vivek Gautam <vivek.gautam@codeaurora.org>
Cc: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>