net: lpc-enet: fix badzero.cocci warnings

drivers/net/ethernet/nxp/lpc_eth.c:1316:31-32: WARNING comparing pointer to 0

 Compare pointer-typed values to NULL rather than 0

Semantic patch information:
 This makes an effort to choose between !x and x == NULL.  !x is used
 if it has previously been used with the function used to initialize x.
 This relies on type information.  More type information can be obtained
 using the option -all_includes and the option -I to specify an
 include path.

Generated by: scripts/coccinelle/null/badzero.cocci

Link: https://lore.kernel.org/r/20190809144043.476786-9-arnd@arndb.de
Fixes: e42016eb3844 ("net: lpc-enet: allow compile testing")
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/net/ethernet/nxp/lpc_eth.c

@@ -1312,7 +1312,7 @@ static int lpc_eth_drv_probe(struct platform_device *pdev)
 		}
 	}
 
-	if (pldat->dma_buff_base_v == 0) {
+	if (pldat->dma_buff_base_v == NULL) {
 		ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
 		if (ret)
 			goto err_out_free_irq;