spi: offload: check offload ops existence before disabling the trigger

Add a safe guard in spi_offload_trigger to check the existence of
offload->ops before invoking the trigger_disable callback

Signed-off-by: Andres Urian Florez <andres.emb.sys@gmail.com>
Link: https://patch.msgid.link/20250608230422.325360-1-andres.emb.sys@gmail.com


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