Move the code which sets up the SG descriptor out of hpsa_scatter_gather()
and into a subroutine where it can be reused (in the next patch).  The Ext
field is now assigned unconditionally: this makes the refactor much simpler,
but more importantly it removes a conditional operation from inside the
loop.  The case for which the conditional formerly tested is now executed
(unconditionally) after the loop is exited.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>