drivers: spi: nrfx: Use HAS_HW_NRF_* in driver options dependencies

Use the HAS_HW_NRF_* symbols instead of the SOC_SERIES_NRF* ones
to filter out the driver options unavailable on particular SoCs.

Add comments explaining why the SPIM driver is not available for
nRF52832.

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