staging: mt7621-gpio: remove redundant owner assignments of drivers

Remove the reduntant owner initialization from this platform driver as
the platform_driver_register() takes care of it.

Signed-off-by: HariPrasath Elango <hariprasath.elango@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>