MAINTAINERS: Add Krzysztof as PCI host/endpoint controllers reviewer

MAINTAINERS: Add Krzysztof as PCI host/endpoint controllers reviewer

Krzysztof has been carrying out PCI patches review for a long time and
he has been instrumental in driving PCI host/endpoint controller drivers
improvements.

Make his role official.

Link: https://lore.kernel.org/r/20210511150003.1592-1-lorenzo.pieralisi@arm.com
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Krzysztof Wilczyński <kw@linux.com>