drivers: ieee802154: Let the initialization priority be done via Kconfig

Since the whole init level changes: all drivers and most of subsystems
are initialized at level POST_KERNEL. Unfortunately that broke legacy
tweaks on what to start first and after.

Let's raise cc2520 priority, still below net_init.

Jira: ZEP-1261

Change-Id: I0d91aa87a893584b3f5b39a193c823127961402f
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

drivers/ieee802154/Kconfig

@@ -151,6 +151,15 @@ config TI_CC2520_AUTO_ACK
 	thus the above stack needs to provide the right information for such
 	filtering feature to work.
 
+config TI_CC2520_INIT_PRIO
+	int "CC2520 intialization priority"
+	default 80
+	help
+	Set the initialization priority number. Do not mess with it unless
+	you know what you are doing. Beware cc2520 requires gpio and spi to
+	be ready first (and sometime gpio should be the very first as spi
+	might need it too). And of course it has to start before the net stack.
+
 endif
 
 config UPIPE_15_4

drivers/ieee802154/ieee802154_cc2520.c

@@ -1058,12 +1058,12 @@ static struct ieee802154_radio_api cc2520_radio_api = {
 #if defined(CONFIG_TI_CC2520_RAW)
 DEVICE_AND_API_INIT(cc2520, CONFIG_TI_CC2520_DRV_NAME,
 		    cc2520_init, &cc2520_context_data, NULL,
-		    APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
+		    POST_KERNEL, CONFIG_TI_CC2520_INIT_PRIO,
 		    &cc2520_radio_api);
 #else
 NET_DEVICE_INIT(cc2520, CONFIG_TI_CC2520_DRV_NAME,
 		cc2520_init, &cc2520_context_data, NULL,
-		CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
+		CONFIG_TI_CC2520_INIT_PRIO,
 		&cc2520_radio_api, IEEE802154_L2,
 		NET_L2_GET_CTX_TYPE(IEEE802154_L2), 127);
 #endif