mpt2sas: Add free smids to the head, not tail of list
mpt2sas: Add free smids to the head, not tail of list

Reusing a smid quickly means it's still cache-hot.  This yields a small
but noticable performance improvement in a well-known database benchmark.
This improvement is already present in the mpt3sas driver.

Signed-off-by: Matthew Wilcox <ed1245e46949b7b8f2bca25d41520ebc8aeefcf8@intel.com>
Reviewed-by: Nicholas Bellinger <978acd1567d5598152161fdf8bf3ca568f950c9b@linux-iscsi.org>
Reviewed-by: Praveen Krishnamoorthy <4ce889eab45d6136cabda8e76fed74e68d3f08fc@lsi.com>
Acked-by: Sreekanth Reddy <5d8ef29afd278d20bb09eeeb2ee4a503e91e9208@lsi.com>
Signed-off-by: Christoph Hellwig <923f7720577207a44b32e59bbfbea59d27f1ae8e@lst.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs