The enable time for buck regulators was not configured but actually is
essential: consumers, like usb3503, doing hard reset (regulator off/on)
should wait for the regulator to settle.

Configure the enable time according to datasheet.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>