MAINTAINERS: Add PCI MHI endpoint function driver under MHI bus

Add PCI endpoint driver for MHI bus under the MHI bus entry in MAINTAINERS
file.

Link: https://lore.kernel.org/r/20230602114756.36586-10-manivannan.sadhasivam@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>