drivers/rapidio/devices/tsi721_dma.c: adjust six checks for null pointers

checkpatch pointed out the following:

  Comparison to NULL could be written !...

Thus fix the affected source code places.

Link: http://lkml.kernel.org/r/c3e79a1a-891e-cb62-990f-bd99839311b9@users.sourceforge.net
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rapidio/devices/tsi721_dma.c

@@ -222,7 +222,7 @@ static int tsi721_bdma_ch_free(struct tsi721_bdma_chan *bdma_chan)
 	struct tsi721_device *priv = to_tsi721(bdma_chan->dchan.device);
 #endif
 
-	if (bdma_chan->bd_base == NULL)
+	if (!bdma_chan->bd_base)
 		return 0;
 
 	/* Check if DMA channel still running */
@@ -346,7 +346,7 @@ tsi721_desc_fill_init(struct tsi721_tx_desc *desc,
 {
 	u64 rio_addr;
 
-	if (bd_ptr == NULL)
+	if (!bd_ptr)
 		return -EINVAL;
 
 	/* Initialize DMA descriptor */
@@ -370,7 +370,7 @@ tsi721_desc_fill_init(struct tsi721_tx_desc *desc,
 static int
 tsi721_desc_fill_end(struct tsi721_dma_desc *bd_ptr, u32 bcount, bool interrupt)
 {
-	if (bd_ptr == NULL)
+	if (!bd_ptr)
 		return -EINVAL;
 
 	/* Update DMA descriptor */
@@ -555,9 +555,7 @@ static void tsi721_advance_work(struct tsi721_bdma_chan *bdma_chan,
 	 * If there is no data transfer in progress, fetch new descriptor from
 	 * the pending queue.
 	*/
-
-	if (desc == NULL && bdma_chan->active_tx == NULL &&
-					!list_empty(&bdma_chan->queue)) {
+	if (!desc && !bdma_chan->active_tx && !list_empty(&bdma_chan->queue)) {
 		desc = list_first_entry(&bdma_chan->queue,
 					struct tsi721_tx_desc, desc_node);
 		list_del_init((&desc->desc_node));
@@ -796,7 +794,7 @@ static void tsi721_free_chan_resources(struct dma_chan *dchan)
 
 	tsi_debug(DMA, &dchan->dev->device, "DMAC%d", bdma_chan->id);
 
-	if (bdma_chan->bd_base == NULL)
+	if (!bdma_chan->bd_base)
 		return;
 
 	tsi721_bdma_interrupt_enable(bdma_chan, 0);