Add Rahul Tanwar as maintainer for PCIe RC controller driver for the Intel
Lightning Mountain (LGM) Gateway SoC.

Link: https://lore.kernel.org/r/b3249e08155e04ac08d820be3b8da29a913c472a.1625559158.git.rtanwar@maxlinear.comSigned-off-by: Rahul Tanwar <rtanwar@maxlinear.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>