drivers/net/ni65.c: fix sparse warnings: fix signedness

Fix this sparse warnings:
  drivers/net/ni65.c:488:36: warning: incorrect type in argument 2 (different signedness)
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ni65.c

@@ -481,8 +481,9 @@ static int __init ni65_probe1(struct net_device *dev,int ioaddr)
 	else {
 		if(dev->dma == 0) {
 		/* 'stuck test' from lance.c */
-			long dma_channels = ((inb(DMA1_STAT_REG) >> 4) & 0x0f) |
-					    (inb(DMA2_STAT_REG) & 0xf0);
+			unsigned long dma_channels =
+				((inb(DMA1_STAT_REG) >> 4) & 0x0f)
+				| (inb(DMA2_STAT_REG) & 0xf0);
 			for(i=1;i<5;i++) {
 				int dma = dmatab[i];
 				if(test_bit(dma,&dma_channels) || request_dma(dma,"ni6510"))