staging: mt7621-mmc: Don't disables DMA

Current code disables the DMA after the transfer. That only changes
the transfer mode to non-DMA and does not save any power. This is not
necessary any more, because now DMA transfer is always used. The macro
for disabling DMA transfer is also removed, because it is not used any
more.
Signed-off-by: Christian Lütke-Stetzkamp <christian@lkamp.de>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-mmc/sd.c

@@ -199,7 +199,6 @@ static int msdc_rsp[] = {
 #define msdc_fifo_read8()    sdr_read8(MSDC_RXDATA)
 
 #define msdc_dma_on()        sdr_clr_bits(MSDC_CFG, MSDC_CFG_PIO)
-#define msdc_dma_off()       sdr_set_bits(MSDC_CFG, MSDC_CFG_PIO)
 
 #define msdc_retry(expr, retry, cnt) \
 	do {								\
@@ -1282,7 +1281,6 @@ static int msdc_do_request(struct mmc_host *mmc, struct mmc_request *mrq)
 done:
 	if (data != NULL) {
 		host->data = NULL;
-		msdc_dma_off();
 		dma_unmap_sg(mmc_dev(mmc), data->sg, data->sg_len,
 			     mmc_get_dma_dir(data));
 		host->blksz = 0;