video: fbdev: wm8505fb: convert platform driver to use dev_groups

video: fbdev: wm8505fb: convert platform driver to use dev_groups

Platform drivers now have the option to have the platform core create
and remove any needed sysfs attribute files.  So take advantage of that
and do not register "by hand" a sysfs file.

Cc: Tony Prisk <linux@prisktech.co.nz>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20190731124349.4474-9-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>