Add maintainers for Synopsys DesignWare PCIe PMU driver and driver
document.
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231208025652.87192-6-xueshuai@linux.alibaba.comSigned-off-by: Will Deacon <will@kernel.org>