megaraid_sas: Fix validHandles check in I/O path

Syncro firmware supports round robin I/O switching on dual path. Driver
uses validHandles to check for dual path. However, it is supposed to
check for values > 1 (not > 2).

Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>