staging: fwserial: (coding-style) rewrite comparisons to NULL as "!fifo->data"

index 7a3347c..4cd3ed3 100644
@@ -106,7 +106,7 @@ void dma_fifo_free(struct dma_fifo *fifo)
 {
 	struct dma_pending *pending, *next;
 
-	if (fifo->data == NULL)
+	if (!fifo->data)
 		return;
 
 	list_for_each_entry_safe(pending, next, &fifo->pending, link)

@@ -123,7 +123,7 @@ void dma_fifo_reset(struct dma_fifo *fifo)
 {
 	struct dma_pending *pending, *next;
 
-	if (fifo->data == NULL)
+	if (!fifo->data)
 		return;
 
 	list_for_each_entry_safe(pending, next, &fifo->pending, link)

@@ -149,7 +149,7 @@ int dma_fifo_in(struct dma_fifo *fifo, const void *src, int n)
 {
 	int ofs, l;
 
-	if (fifo->data == NULL)
+	if (!fifo->data)
 		return -ENOENT;
 	if (fifo->corrupt)
 		return -ENXIO;

@@ -192,7 +192,7 @@ int dma_fifo_out_pend(struct dma_fifo *fifo, struct dma_pending *pended)
 {
 	unsigned len, n, ofs, l, limit;
 
-	if (fifo->data == NULL)
+	if (!fifo->data)
 		return -ENOENT;
 	if (fifo->corrupt)
 		return -ENXIO;

@@ -252,7 +252,7 @@ int dma_fifo_out_complete(struct dma_fifo *fifo, struct dma_pending *complete)
 {
 	struct dma_pending *pending, *next, *tmp;
 
-	if (fifo->data == NULL)
+	if (!fifo->data)
 		return -ENOENT;
 	if (fifo->corrupt)
 		return -ENXIO;