ARM: dts: sun5i: Move q8 display bits to sun5i-a13-q8-tablet.dts

This is a preparation patch for renaming sun5i-q8-common.dtsi to
sun5i-reference-design-tablet.dtsi and sharing it between all
the A13 tablet dts files.

Since we only have a panel config for the 18 tablets (for now) move
this to the q8 specific dts file.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>