rockchip: rk3568-rock-3a: Enable PCIe and NVMe support

Add missing pinctrl and defconfig options to enable PCIe and NVMe
support on Radxa ROCK 3 Model A.

Use of pcie20m1_pins and pcie30x2m1_pins ensure IO mux selection M1.
The following pcie_reset_h and pcie3x2_reset_h ensure GPIO func is
restored to the perstn pin, a workaround to avoid having to define
a new rockchip,pins.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>