spi: omap2-mcpsi: Enable MULTI-mode in more situations

Enable multimode when a transfer of multiple small words can be
transformed in a transfer with a single bigger word. This is allowed as
long as the result on the cable is the same, so word_delay must be zero.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://msgid.link/r/20240327-spi-omap2-mcspi-multi-mode-v3-3-c4ac329dd5a2@bootlin.com


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