Add compilation flags to rf_configuration

Add flags to allow compilation without nanostack.

Author: Arto Kinnunen

components/802.15.4_RF/stm-s2lp-rf-driver/source/rf_configuration.c

@@ -13,6 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+#if defined(MBED_CONF_NANOSTACK_CONFIGURATION) && DEVICE_SPI && DEVICE_INTERRUPTIN && defined(MBED_CONF_RTOS_PRESENT)
+
 #include "nanostack/platform/arm_hal_phy.h"
 #include "rf_configuration.h"
 
@@ -167,3 +170,6 @@ uint32_t rf_conf_calculate_deviation(phy_modulation_index_e modulation_index, ui
     }
     return deviation;
 }
+
+#endif // MBED_CONF_NANOSTACK_CONFIGURATION && DEVICE_SPI && DEVICE_INTERRUPTIN && defined(MBED_CONF_RTOS_PRESENT)
+