arm64: dts: rockchip: Fix the num-lanes of pcie3x4 on Cool Pi CM5 EVB

The 4 lane pcie30 phy is shared by pcie3x4 and pcie3x2, so
the num-lanes of pcie3x4 should be 2.

Fixes: 791c154c

 ("arm64: dts: rockchip: Add support for rk3588 based board Cool Pi CM5 EVB")
Signed-off-by: Andy Yan <andyshrk@163.com>
Link: https://lore.kernel.org/r/20240201121106.1471301-4-andyshrk@163.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>