modem_cellular: lara_r6: add option to clear forbidden networks from SIM

SIM-cards remember which networks has rejected attach attempts. This is
not always desired if the user has control over which networks to allow.
This commit adds a Kconfig symbol which enables clearing of saved
forbidden networks from SIM-card on boot.

Signed-off-by: Emil Lindqvist <emil@lindq.gr>

Author: emillindq

drivers/modem/Kconfig.cellular

@@ -81,6 +81,9 @@ config MODEM_CELLULAR_RAT_4G_3G_2G
 
 endchoice
 
+config MODEM_CELLULAR_CLEAR_FORBIDDEN
+	bool "Clear forbidden networks from SIM-card on boot"
+
 endif #DT_HAS_U_BLOX_LARA_R6_ENABLED
 
 endif #MODEM_CELLULAR

drivers/modem/modem_cellular.c

@@ -2308,6 +2308,11 @@ MODEM_CHAT_SCRIPT_CMDS_DEFINE(u_blox_lara_r6_init_chat_script_cmds,
 			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+URAT=3,2", ok_match),
 #elif CONFIG_MODEM_CELLULAR_RAT_4G_3G_2G
 			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+URAT=3,2,0", ok_match),
+#endif
+#if CONFIG_MODEM_CELLULAR_CLEAR_FORBIDDEN
+			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+CRSM=214,28539,0,0,12,"
+							 "\"FFFFFFFFFFFFFFFFFFFFFFFF\"",
+							 ok_match),
 #endif
 			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+CGSN", imei_match),
 			      MODEM_CHAT_SCRIPT_CMD_RESP("", ok_match),