spi: spi-loopback-test: Allow skipping delays

spi: spi-loopback-test: Allow skipping delays

A 100 ms delay is inserted between tests by default in order to "detect
the individual tests when using a logic analyzer".  However, such delays
are unnecessary when using this module for automated regression testing,
so allow them to be disabled with a module parameter.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20230103152211.3034779-1-vincent.whitchurch@axis.com
Signed-off-by: Mark Brown <broonie@kernel.org>