regulator: as3722: Add bypass support for LDO6

LD06 on the AS3722 power management IC supports a bypass mode. Bypass
is enabled for the LDO by writing the value 0x3F to the voltage select
field in the control register for the LDO. Note that this is the same
register and field that is used to select the voltage as well for the
LDO.

Add support for bypass on LDO6 by specifying the various bypass
parameters for regulator and adding new function pointer tables for the
LDO. Note that the bypass OFF value is the same as the ON value simply
because there is no actual OFF value and bypass will be disabled when
a new voltage is written to the VSEL field.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>