Clean the iomux definitions at grf_rk322x.h, and move them into
pinctrl-driver for resolving the compiling error of redefinition.
After that, define the uart2 iomux at rk322x-board file.
Signed-off-by: David Wu <david.wu@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>