Bluetooth: controller: Move nRF5 specific debug pins to hal/nrf5

Move the nRF5 specific GPIO debug pin macro definitions to
hal/nrf5/debug.h.

The Controller's hal folder contains prototypes and
hal/<soc> shall contain SoC specific implementation to
realize a software-based Link Layer.

Change-id: Ic7bf283f926bbc3069e7d15c047fe93a6daa894f
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>