MAINTAINERS: add Guvenc as SMC maintainer

Add Guvenc as maintainer for Shared Memory Communications (SMC)
Sockets.

Cc: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: NGuvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -16554,6 +16554,7 @@ F:	drivers/misc/sgi-xp/
 
 SHARED MEMORY COMMUNICATIONS (SMC) SOCKETS
 M:	Karsten Graul <kgraul@linux.ibm.com>
+M:	Guvenc Gulce <guvenc@linux.ibm.com>
 L:	linux-s390@vger.kernel.org
 S:	Supported
 W:	http://www.ibm.com/developerworks/linux/linux390/