drivers: wifi: Remove nRF specific boards coupling

These can be used by customer boards as well, so, remove the nRF board
dependency and instead rely on customer providing the necessary DTS
entries.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>

drivers/wifi/nrf700x/Kconfig

@@ -263,7 +263,7 @@ config NRF700X_UTIL
 
 config NRF700X_SR_COEX
 	bool "Enable Wi-Fi and SR coexistence support"
-	default y if SOC_NRF5340_CPUAPP_QKAA
+	def_bool $(dt_nodelabel_enabled,nrf_radio_coex)
 
 config NRF700X_QSPI_LOW_POWER
 	bool "Enable low power mode in QSPI"