treewide: convert gpio-export to platform driver

treewide: convert gpio-export to platform driver

Without this patch you will get an error "gpio-export probe deferral
not supported" when you try to export i2c expander gpio pins.

gpio-export is probed long before i2c-bus and i2c expander are created
and it doesn't retry it so none pins are exported.

Signed-off-by: René van Dorst <opensource@vdorst.com>
apply the change to all instances of the gpio exports patch
Signed-off-by: Mathias Kresin <dev@kresin.me>
(backported from 0ae9396556584db2dac73364af44758a5ccf4873)