[IA64] unwind - optimise linked-list searches for modules

It's clear from the comment in the code about keeping the
kernel's unwind table at the front of the list that some
attention has been paid to access patterns. Tests on other
architectures have shown that a move-to-front optimisation
improves searches dramatically.

Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>