MLK-17258 ARM64: dts: add off-on-delay for usdhc vmmc-supply regulator

MLK-17258 ARM64: dts: add off-on-delay for usdhc vmmc-supply regulator

For the slot support SD3.0 card, during system suspend, if plug out
the sd card, and insert another SD3.0 card, after system resume back,
SD3.0 card can't be recognized as SD3.0 card, just SD2.0 card.

This is because the time delay between vmmc regulator off and on is
too small. SD spec require the Card Vdd shall be lowered to less than
0.5v for a minimum period for 1ms. And the hardware regulator also need
some time to drop the Card Vdd from 3.3v to 0.5v. This patch add the
off-on-delay in vmmc-supply regulator adding the upper two limitation
into consideration.

This patch relay on the commit 878bff7648f5 ("MLK-14638-1 regulator:
fixed: add off_on_delay support").

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>