drivers: spi_nrfx_spim: Add clock requests for fast SPIM instances

Fast SPIM instances (SPIM120 and SPIM121) for correct operation require
the highest frequency from the global HSFLL. This commit adds needed
clock controller requests to the driver. When the runtime device power
management is enabled, the frequency is requested as long as the SPIM
is resumed, otherwise it is requested for the duration of transfers.

This commit also adds a missing call to `pm_device_runtime_put()` when
SPIM reconfiguration fails.

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