Add entries for the mp8859 regulator driver
to the build system.
Signed-off-by: NMarkus Reichl <m.reichl@fivetechno.de>
Link: https://lore.kernel.org/r/20200106211633.2882-3-m.reichl@fivetechno.deSigned-off-by: NMark Brown <broonie@kernel.org>