rockchip: rk3288: Add support for drive-strength in PINCTRL

rockchip: rk3288: Add support for drive-strength in PINCTRL

Currently, drive-strenght to 12ma are described and supposed to be used
on RK3288. However, the pinctrl driver for this SoC only handles muxing
and pull up/pull down via PU/PD control registers. So complex IPs like
GMAC are working in normal ethernet 100mbps, but not at 1gbps typically.

This commit adds support for handling drive-strength of 12ma, when it's
defined in the DT.

Signed-off-by: Romain Perier <[email protected]>
Acked-by: Philipp Tomsich <[email protected]>
Reviewed-by: Philipp Tomsich <[email protected]>