Changing the card voltage on the cc is not instantaneous, especially
when switching from 3.3v to 1.8v.

It take at least 30ms for the regulator to go from 3.3v to 1.8v. Add
margin to that to make sure we don't upset the sdcard during the voltage
switch

Fixes: 61ff2af9b278 ("ARM64: dts: fixup libretech cc definition")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>