staging/sm7xxfb: Convert to SIMPLE_DEV_PM_OPS

Instead of assigning the pm_ops fields individually we can simply use
SIMPLE_DEV_PM_OPS.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Acked-by: Javier Muñoz <jmunhoz@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>