scsi: mpt3sas: remove obsolete path "drivers/scsi/mpt2sas/" from MAINTAINERS

drivers/scsi/mpt2sas/ no longer exists after commit
c84b06a4 ("mpt3sas: Single driver module which supports both SAS 2.0 &
SAS 3.0 HBAs") merged/removed it.

Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>