Bluetooth: controller: Fix disabling of Coded PHY feature

Fix conditional compilation in nRF5 radio interface so that
when Coded PHY feature is not selected then it does not use
the PPIs required for supporting the feature.

This will allow pwm_nrf5_sw driver to use PPI channels 14 to
19 and support 3 PWM channels. Without the Coded PHY feature
disabled, only PPI 14, 15, 18 and 19 are available for PWM.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>