arm64: dts: rockchip: add variables for pcie completion to helios64

without ep-gpios defined u-boot does not initialise PCIe
rockchip_pcie pcie@f8000000: failed to find ep-gpios property

additionally set max-link-speed and pinctrl-names for completeness

with this patch and the ones from Florian Klink applied to the dts
file in u-boot sata drives show up in both u-boot and linux
Signed-off-by: Dennis Gilmore <dgilmore@redhat.com>
Acked-By: Florian Klink <flokli@flokli.de>
Link: https://lore.kernel.org/r/20211029005323.144652-1-dgilmore@redhat.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts

@@ -401,7 +401,10 @@ &pcie_phy {
 };
 
 &pcie0 {
+	ep-gpios = <&gpio2 RK_PD4 GPIO_ACTIVE_HIGH>;
+	max-link-speed = <2>;
 	num-lanes = <2>;
+	pinctrl-names = "default";
 	status = "okay";
 
 	vpcie12v-supply = <&vcc12v_dcin>;