regmap: Use flexible sleep

The multi-reg write function uses udelay(), which is a busy-loop based
delaying function that is not suitable for a long delays. Hence let's
replace the udelay() with fsleep(), which is flexible sleep function that
selects best delay function based on the delay-time.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20200830185356.5365-3-digetx@gmail.com


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