arm64: dts: rockchip: fix input enable pinconf on rk3399

When the input enable pinconf was introduced, a default drive-strength
value of 2 was set for the pull up/down configs. However, this parameter
is unneeded when configuring the pin as input, and having a single
hardcoded value here is actually harmful: GPIOs on the RK3399 have
various same drive-strength capabilities depending on the bank and port
they belong to.

As an example, trying to configure the GPIO4_PD3 pin as an input with
pull-up enabled fails with the following output:

  [   10.706542] rockchip-pinctrl pinctrl: unsupported driver strength 2
  [   10.713661] rockchip-pinctrl pinctrl: pin_config_set op failed for pin 155

(acceptable drive-strength values for this pin being 3, 6, 9 and 12)

Let's drop the drive-strength property from all input pinconfs in order
to solve this issue.

Fixes: ec48c3e8

 ("arm64: dts: rockchip: add an input enable pinconf to rk3399")
Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
Reviewed-by: Caleb Connolly <kc@postmarketos.org>
Link: https://lore.kernel.org/r/20221215101947.254896-1-arnaud.ferraris@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>