drivers: modem: fix thread function signatures

Fix thread function signatures to avoid stack corruption on thread exit.

Signed-off-by: Benedikt Schmidt <benedikt.schmidt@embedded-solutions.at>
diff --git a/drivers/modem/simcom-sim7080.c b/drivers/modem/simcom-sim7080.c
index 39fb66b..b6a159e 100644
--- a/drivers/modem/simcom-sim7080.c
+++ b/drivers/modem/simcom-sim7080.c
@@ -802,8 +802,12 @@
 /*
  * Process all messages received from the modem.
  */
-static void modem_rx(void)
+static void modem_rx(void *p1, void *p2, void *p3)
 {
+	ARG_UNUSED(p1);
+	ARG_UNUSED(p2);
+	ARG_UNUSED(p3);
+
 	while (true) {
 		/* Wait for incoming data */
 		modem_iface_uart_rx_wait(&mctx.iface, K_FOREVER);
@@ -2414,7 +2418,7 @@
 	}
 
 	k_thread_create(&modem_rx_thread, modem_rx_stack, K_KERNEL_STACK_SIZEOF(modem_rx_stack),
-			(k_thread_entry_t)modem_rx, NULL, NULL, NULL, K_PRIO_COOP(7), 0, K_NO_WAIT);
+			modem_rx, NULL, NULL, NULL, K_PRIO_COOP(7), 0, K_NO_WAIT);
 
 	/* Init RSSI query */
 	k_work_init_delayable(&mdata.rssi_query_work, modem_rssi_query_work);