regulator: Fix MFD_MAX597X dependency

Drivers should depend on rather than select their MFDs.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220707111753.16581-1-broonie@kernel.org


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