MAINTAINERS: Delete generic_serial section

commit bb2a97e9 ("Staging: delete generic_serial drivers")
removed the files, delete the section.

CC: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

MAINTAINERS

@@ -184,11 +184,6 @@ S:	Maintained
 F:	Documentation/filesystems/9p.txt
 F:	fs/9p/
 
-A2232 SERIAL BOARD DRIVER
-L:	linux-m68k@lists.linux-m68k.org
-S:	Orphan
-F:	drivers/staging/generic_serial/ser_a2232*
-
 AACRAID SCSI RAID DRIVER
 M:	Adaptec OEM Raid Solutions <aacraid@adaptec.com>
 L:	linux-scsi@vger.kernel.org