There is no reason to have such a tight usleep range of 400us and it is
acceptable to allow MIN_US * 2.

Also wrap the usleep in an inline function.
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/168147949455.26.3401634900657387799@mailman-core.alsa-project.orgSigned-off-by: Mark Brown <broonie@kernel.org>