net: iosm: Prevent underflow in ipc_chnl_cfg_get()

The bounds check on "index" doesn't catch negative values.  Using
ARRAY_SIZE() directly is more readable and more robust because it prevents
negative values for "index".  Fortunately we only pass valid values to
ipc_chnl_cfg_get() so this patch does not affect runtime.
Reported-by: Solomon Ucko <solly.ucko@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/iosm/iosm_ipc_chnl_cfg.c

@@ -64,10 +64,9 @@ static struct ipc_chnl_cfg modem_cfg[] = {
 
 int ipc_chnl_cfg_get(struct ipc_chnl_cfg *chnl_cfg, int index)
 {
-	int array_size = ARRAY_SIZE(modem_cfg);
-
-	if (index >= array_size) {
-		pr_err("index: %d and array_size %d", index, array_size);
+	if (index >= ARRAY_SIZE(modem_cfg)) {
+		pr_err("index: %d and array size %zu", index,
+		       ARRAY_SIZE(modem_cfg));
 		return -ECHRNG;
 	}