MAINTAINERS: remove John Allen from ibmvnic

John's email has bounced and Thomas confirms he no longer
works on ibmvnic.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: kuba-moo

MAINTAINERS

@@ -8322,7 +8322,6 @@ F:	drivers/pci/hotplug/rpaphp*
 
 IBM Power SRIOV Virtual NIC Device Driver
 M:	Thomas Falcon <tlfalcon@linux.ibm.com>
-M:	John Allen <jallen@linux.ibm.com>
 L:	netdev@vger.kernel.org
 S:	Supported
 F:	drivers/net/ethernet/ibm/ibmvnic.*