remoteproc: imx_rproc: Skip over memory region when node value is NULL

In imx_rproc_addr_init() "nph = of_count_phandle_with_args()" just counts
number of phandles. But phandles may be empty. So of_parse_phandle() in
the parsing loop (0 < a < nph) may return NULL which is later dereferenced.
Adjust this issue by adding NULL-return check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: a0ff4aa6 ("remoteproc: imx_rproc: add a NXP/Freescale imx_rproc driver")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240606075204.12354-1-amishin@t-argos.ru
[Fixed title to fit within the prescribed 70-75 charcters]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/imx_rproc.c

@@ -726,6 +726,8 @@ static int imx_rproc_addr_init(struct imx_rproc *priv,
 		struct resource res;
 
 		node = of_parse_phandle(np, "memory-region", a);
+		if (!node)
+			continue;
 		/* Not map vdevbuffer, vdevring region */
 		if (!strncmp(node->name, "vdev", strlen("vdev"))) {
 			of_node_put(node);