IB/hfi1: Fix SL array bounds check

The SL specified by a user needs to be a valid SL.

Add a range check to the user specified SL value which protects from
running off the end of the SL to SC table.

CC: stable@vger.kernel.org
Fixes: 77241056 ("IB/hfi1: add driver files")
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>