staging: hikey9xx: hi6421v600-regulator: move LDO config from DT

Instead of storing regulator LDO configuration inside the DT, move
it to be part of the driver itself.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/46b16fdf4ad924b5d9a06139cd7ff2dae28d5a6c.1611212783.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>