The PWM decodeer, in LOAD=Single mode, loads data in groups of 4
half-words. Previously, if any channel was not connected to a pin (a
connection that's immaterial to the loader), a smaller number would be
given resulting in the decoder not loading anything at all.
See-Also: https://infocenter.nordicsemi.com/pdf/nRF52840_PS_v1.1.pdf#page=256
Once PWM is running, the active PWM module overrides the PIN_CNF state;
only when PWM is stopped the pin returns into its PIN_CNF state (which,
then, the board may set to whatever idle means there).
(Moreover, the code there only worked for P0 registers, not eg. the
P1.09 of the nrf52840dongle's RGB LED).
