spi: intel: Implement adjust_op_size()

This allows us to get rid of the checks in the intel_spi_[sh]w_cycle()
and makes it possible for the SPI-NOR core to split the transaction into
smaller chunks as needed.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20221025064623.22808-3-mika.westerberg@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>