drm/nouveau/backlight: Just set all backlight types as RAW

Currently we can get a warning on systems with eDP backlights like so:

  nv_backlight: invalid backlight type
  WARNING: CPU: 4 PID: 454 at drivers/video/backlight/backlight.c:420
    backlight_device_register+0x226/0x250

This happens as a result of us not filling out props.type for the eDP
backlight, even though we do it for all other backlight types.

Since nothing in our driver uses anything but BACKLIGHT_RAW, let's take the
props\.type assignments out of the codepaths for individual backlight types
and just set it unconditionally to prevent this from happening again.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: 6eca310e ("drm/nouveau/kms/nv50-: Add basic DPCD backlight support for nouveau")
Cc: <stable@vger.kernel.org> # v5.15+
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220204193319.451119-1-lyude@redhat.com