spi: fsl-spi: Change mspi_apply_cpu_mode_quirks() to void

mspi_apply_cpu_mode_quirks() always returns the passed bits_per_word
unmodified.

Make it return void, then don't check bits_per_word anymore on
return as it doesn't change.

bits_per_word is already checked by __spi_validate() so no risk to
have bits_per_word higher than 32.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/3142a7c40af12a160f4e134764f2c34da3d8e1e2.1680371809.git.christophe.leroy@csgroup.eu


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