net: octeontx2: NULL check before dereference

In rvu_af_init if the code fails to allocate memory for nix_af it will
take the error path with nix_af == NULL which will dereference nix_af.
Add the appropriate NULL check.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>

drivers/net/octeontx2/rvu_af.c

@@ -114,7 +114,7 @@ struct nix_af *rvu_af_init(struct rvu_af *rvu_af)
 	return nix_af;
 
 error:
-	if (nix_af->npa_af) {
+	if (nix_af && nix_af->npa_af) {
 		free(nix_af->npa_af);
 		memset(nix_af, 0, sizeof(*nix_af));
 	}