iwlwifi: dbg_ini: fix memory leak in alloc_sgtable

commit b4b814fec1a5a849383f7b3886b654a13abbda7d upstream.

In alloc_sgtable if alloc_page fails, the alocated table should be
released.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>