arm64: dts: rockchip: rockpro64 dts remove unused lcd-reset pinmux

lcd panel pinmux is unused and the pin actually for something different,
so removing it.

Signed-off-by: Akash Gajjar <Akash_Gajjar@mentor.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>