MAINTAINERS: Add Manivannan Sadhasivam as PCI Endpoint maintainer

The PCI endpoint subsystem is evolving at a rate I cannot keep up with,
therefore I am standing down as a maintainer handing over to Manivannan
(currently reviewer for this code) and Krzysztof who are doing an excellent
job on the matter - they don't need my help any longer.

Link: https://lore.kernel.org/r/20240129165933.33428-1-lpieralisi@kernel.org


Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Krzysztof Wilczyński <kw@linux.com>