arm64: dts: rockchip: move uart2 pinmux to dtsi on rk3588-tiger

arm64: dts: rockchip: move uart2 pinmux to dtsi on rk3588-tiger

The association of uart2 to the q7-uart pins is part of the module
itself and not the baseboard used. Therefore move the pinctrl over
to the tiger dtsi.

Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Link: https://lore.kernel.org/r/20240422143356.2596414-1-heiko@sntech.de
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
[ upstream commit: 5adbad5c464a708a87cf5ade1bfe2ca947bb2f82 ]

(cherry picked from commit f8314a4fbc00a3d651a7e9b4d9462d10c6c02a12)