mmc: mmci: Break out a helper function

These four lines clearing, masking and resetting the state
of the busy detect state machine is repeated five times in
the code so break this out to a small helper so things are
easier to read.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v7-9-69a7164f2a61@linaro.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>