msm: ipa: Avoid buffer over read of smmu ctx

To avoid the the smmu cb ctx read if smmu is bypassed.

Change-Id: I0b23d413365d9b36cdf560605c9c221f155624cb
Signed-off-by: Michael Adisumarta <[email protected]>

drivers/platform/msm/ipa/ipa_v3/ipa_nat.c

@@ -145,7 +145,7 @@ static int ipa3_nat_ipv6ct_mmap(
 	/*
 	 * Check if no smmu or non dma coherent
 	 */
-	if (!cb->valid || !dev_is_dma_coherent(cb->dev)) {
+	if (cb && (!cb->valid || !dev_is_dma_coherent(cb->dev))) {
 
 		IPADBG("Either smmu valid=%u and/or DMA coherent=%u false\n",
 			   cb->valid, !dev_is_dma_coherent(cb->dev));