Some LCD panels have back-powering issue when un-powered, allows users
to use an alternate pinctrl "sleep" in order to clamp outputs to a
wanted state at suspend.
Signed-off-by: NSylvain Rochet <sylvain.rochet@finsecur.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>