drivers: clock_control: nrf2: align with hw binding names

Currently there is a mismatch between the naming of the hardware and
the drivers targetting the hardware. nrf2_ is used instead of
the actual bindings names, like nrf2_audiopll instead of
nrfs_audiopll. This makes it hard to map drivers to the hardware
they are targetting.

There is historical reason for some of this, namely the same binding
name was used for different hardware, which is why nrf2_ was used
on newer platforms. This is no longer the case though, so drivers
and configs can be named according to the hardware without conflict.

Signed-off-by: Bjarki Arge Andreasen <bjarki.andreasen@nordicsemi.no>