MAINTAINERS: update cxgb4vf maintainer to Vishal

Casey Leedomn <leedom@chelsio.com> is bouncing,
Vishal indicated he's happy to take the role.

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

MAINTAINERS

@@ -4571,7 +4571,7 @@ F:	drivers/infiniband/hw/cxgb4/
 F:	include/uapi/rdma/cxgb4-abi.h
 
 CXGB4VF ETHERNET DRIVER (CXGB4VF)
-M:	Casey Leedom <leedom@chelsio.com>
+M:	Vishal Kulkarni <vishal@gmail.com>
 L:	netdev@vger.kernel.org
 W:	http://www.chelsio.com
 S:	Supported