regulator: bd718x7: Bypass bogus warnings

regulator: bd718x7: Bypass bogus warnings

When regulator consumer attempts to set enabled DVS regulator voltage,
the driver aborts with "Only DVS bucks can be changed when enabled".
In case the regulator is already set to specified voltage, do nothing
instead of failing outright.

When regulator consumer attempts to set enables regulator which cannot
be controlled because it is already always enabled, the driver aborts
with -EINVAL. Again, do nothing in such case and return 0, because the
request is really fulfilled, the regulator is enabled.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>