[nrf fromtree] net: wifi: Fix PEM certificate parsing errors

MbedTLS specifically checks for null-terminator, else it skips PEM
format processing and tries to parse it as DER causing parsing failures.

Signed-off-by: Chaitanya Tata <[email protected]>
(cherry picked from commit 4c5a72f)

Author: krish2718

subsys/net/l2/wifi/wifi_shell.c

@@ -32,14 +32,17 @@ LOG_MODULE_REGISTER(net_wifi_shell, LOG_LEVEL_INF);
 #ifdef CONFIG_WIFI_NM_WPA_SUPPLICANT_CRYPTO_ENTERPRISE
 static const char ca_cert_test[] = {
 	#include <wifi_enterprise_test_certs/ca.pem.inc>
+	'\0'
 };
 
 static const char client_cert_test[] = {
 	#include <wifi_enterprise_test_certs/client.pem.inc>
+	'\0'
 };
 
 static const char client_key_test[] = {
 	#include <wifi_enterprise_test_certs/client-key.pem.inc>
+	'\0'
 };
 #endif