arm64: dts: rockchip: enable the mali GPU on rk3399-firefly

The Firefly RK3399 device tree had the GPU status set to disabled as per
the default from the rk3399.dtsi. This patch sets the status in the
firefly dts to enable it for use. Tested successfully on a 2GB Firefly
RK3399 board.

Signed-off-by: Michael Saunders <mick.saunders@gmail.com>
Link: https://lore.kernel.org/r/20220207073617.7386-1-mick.saunders@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>