ARM: dts: Copy sun8i-q8-common.dtsi sun8i-reference-design-tablet.dtsi

Copy sun8i-q8-common.dtsi to sun8i-reference-design-tablet.dtsi. This
is part of renaming all the sun?i-q8-common.dtsi files to
sun?i-reference-design-tablet.dtsi since most of the hw-config in there
is shared by all sunxi tablets.

Note that in this case we keep sun5i-q8-common.dtsi as it is shared
between a23 / a33 q8 tablets. Also we leave the usb-wifi config in
there (rather then in sun8i-reference-design-tablet.dtsi) as most
sun8i tablets use sdio wifi rather then usb wifi.

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