sata_fsl,mv,nv: prepare for NCQ command completion update

sata_fsl,mv,nv: prepare for NCQ command completion update

Make the following changes to prepare for NCQ command completion
update.  Changes made by this patch don't cause any functional
difference.

* sata_fsl_host_intr(): rename the local variable qc_active to
  done_mask as that's what it is.

* mv_process_crpb_response(): restructure if clause for easier update.

* nv_adma_interrupt(): drop unnecessary error variable.

* nv_swncq_sdbfis(): drop unnecessary nr_done and return 0 on success.
  Typo fix.

* nv_swncq_dmafis(): drop unused return value and return void.

* nv_swncq_host_interrupt(): drop unnecessary return value handling.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ashish Kalra <ashish.kalra@freescale.com>
Cc: Saeed Bishara <saeed@marvell.com>
Cc: Mark Lord <liml@rtr.ca>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>