ASoC: mchp-spdiftx: use FIELD_PREP() where possible

Use FIELD_PREP() in macro definitions.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221213112851.89212-5-claudiu.beznea@microchip.com


Signed-off-by: Mark Brown <broonie@kernel.org>