When the mic-gnd contacts are short-circuited by a headphones plug, the
hardware periodically retries if it can apply the bias-current leading to
the OVCD status flip-flopping 1-0-1 with it being 0 about 10% of the time.
This commit enables the sticky bit for the OVCD status to deal with this.

This commit also introduces 2 helper functions to deal with the OVCD
status bit, this may seem a bit overkill now, but these will also be
used in future patches.
Tested-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>