MAINTAINERS: Remove Wenrui Li as Rockchip PCIe driver maintainer

Wenrui Li changed his employer and is no longer able to maintain the
Rockchip PCIe driver, so remove his email address from this file.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>