zephyr: default to NRF_SECURITY when used with NCS

NRF_SECURITY is only available for Nordic targets (there is a 'depends on'
guarding that). This makes it easy to enable NRF_SECURITY whenever it is
available (NCS in use, with Nordic SoC).

NRF_SECURITY pulls MBEDTLS_TLS_LIBRARY as dependency. Then all the required
configuration already is in place, as it was implemented for nrf9160dk
before.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

Author: mniestroj

port/zephyr/Kconfig

@@ -20,6 +20,7 @@ menuconfig GOLIOTH_FIRMWARE_SDK
 	imply DNS_RESOLVER if NET_NATIVE
 	imply NET_SOCKETS_SOCKOPT_TLS
 	imply NET_SOCKETS_ENABLE_DTLS
+	imply NRF_SECURITY if ZEPHYR_NRF_MODULE
 	help
 	  Enable library for communication with Golioth cloud.