MAINTAINERS: Remove myself as maintainer

I am leaving IBM and will move on to other working area,
so remove myself as a vfio-ccw maintainer.
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.ibm.com>

Message-Id: <20180706015743.41810-1-bjsdjshi@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

MAINTAINERS

@@ -12384,7 +12384,6 @@ F:	drivers/pci/hotplug/s390_pci_hpc.c
 
 S390 VFIO-CCW DRIVER
 M:	Cornelia Huck <cohuck@redhat.com>
-M:	Dong Jia Shi <bjsdjshi@linux.ibm.com>
 M:	Halil Pasic <pasic@linux.ibm.com>
 L:	linux-s390@vger.kernel.org
 L:	kvm@vger.kernel.org