regulator: wm8994: Add an off-on delay for WM8994 variant

As per Table 130 of the wm8994 datasheet at [1], there is an off-on
delay for LDO1 and LDO2.  In the wm8958 datasheet [2], I could not
find any reference to it.  I could not find a wm1811 datasheet to
double-check there, but as no one has complained presumably it works
without it.

This solves the issue on Samsung Aries boards with a wm8994 where
register writes fail when the device is powered off and back-on
quickly.

[1] https://statics.cirrus.com/pubs/proDatasheet/WM8994_Rev4.6.pdf
[2] https://statics.cirrus.com/pubs/proDatasheet/WM8958_v3.5.pdf



Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/CY4PR04MB056771CFB80DC447C30D5A31CB1D9@CY4PR04MB0567.namprd04.prod.outlook.com


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