modules: hal_nordic: Refactor nrfx related Kconfig options

Change dependencies of the Kconfig options that enable particular nrfx
drivers so that the drivers and their instances are available when
a devicetree node with a corresponding compatible property exists,
no matter if it is enabled or not.
Change the options that enable compilation of multi-instance drivers
to be promptless helpers only (not directly configurable for users),
as they need to be enabled only together with some options that enable
particular instances of a given driver, and those options select them
as needed.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>