soc: arm: nordic_nrf: Clean up and unify a bit cmake code

Consistently use `zephyr_library*` cmake functions for all nRF Series
and set the Cortex-M linker script in a common place for all of them.
Remove no longer needed include directories.

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