regulator: da9063: Add support for full-current mode.

In addition to the ability of merging some power outputs, this chip has
an overdrive mode.
BCORE1, BCORE2 and BPRO have this ability, in which case the legal
current draw is increased from 2 amps to 2.5 amps (at the expense of
a quiescent current increase), and the configurable current limits
are doubled.
If a current higher than maximum half-current mode is requested, enable
overdrive, and scale the current limit down.
Symmetrically, scale the current limit up when querying a overdrive-enabled
regulator.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Link: https://lore.kernel.org/r/824518e6391b783a12eba9ff0527f06607a34bfb.1626160826.git.plr.vincent@gmail.com


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