nxp: combine MONOLITHIC_BT and MONOLITHIC_IEEE802154

Combine BLE and 802.15.4 monolithic build under a single config to make
it less error prone.
The choice between a BLE/802.15.4 combo firmware and a BLE only firmware
is done depending on the Soc (like RW610 vs RW612).

Signed-off-by: Axel Le Bourhis <axel.lebourhis@nxp.com>

soc/nxp/rw/Kconfig

@@ -17,7 +17,7 @@ config SOC_SERIES_RW6XX
 	select HAS_MCUX_FLEXCOMM
 	select HAS_MCUX_CACHE
 	select HAS_PM
-	select HAS_NXP_MONOLITHIC_BT
+	select HAS_NXP_MONOLITHIC_NBU
 	select SOC_EARLY_INIT_HOOK
 
 if SOC_SERIES_RW6XX

soc/nxp/rw/Kconfig.defconfig

@@ -14,10 +14,10 @@ config SYS_CLOCK_HW_CYCLES_PER_SEC
 	default 1000000 if MCUX_OS_TIMER
 	default 260000000 if CORTEX_M_SYSTICK
 
-if BT
+config NXP_MONOLITHIC_NBU
+	default y if (BT || IEEE802154)
 
-config NXP_MONOLITHIC_BT
-	default y
+if BT
 
 config HCI_NXP_ENABLE_AUTO_SLEEP
 	default y

soc/nxp/rw/firmwares.ld

@@ -15,7 +15,7 @@ KEEP(*(.fw_cpu1))
 . += 4;
 #endif
 
-#if defined(CONFIG_NXP_MONOLITHIC_BT)
+#if defined(CONFIG_NXP_MONOLITHIC_NBU)
 . = ALIGN(4);
-KEEP(*(.fw_cpu2_ble))
+KEEP(*(.fw_cpu2))
 #endif