MAINTAINERS: Update s390/pci maintainer

Update maintainer entry for s390 PCI subsystem.
Sebastian has left IBM, Niklas takes over maintainership.
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

MAINTAINERS

@@ -14503,7 +14503,7 @@ S:	Supported
 F:	drivers/s390/net/
 
 S390 PCI SUBSYSTEM
-M:	Sebastian Ott <sebott@linux.ibm.com>
+M:	Niklas Schnelle <schnelle@linux.ibm.com>
 M:	Gerald Schaefer <gerald.schaefer@de.ibm.com>
 L:	linux-s390@vger.kernel.org
 W:	http://www.ibm.com/developerworks/linux/linux390/