regulator: dt-bindings: Revise the rt5190a buck/ldo description

Revise the rt5190a bucks and ldo property description.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1650610255-6180-1-git-send-email-u0084500@gmail.com


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