[IA64] MCA recovery: Montecito support

The information in MCA records is filled in slightly differently on
Montecito than on Madison/McKinley.  Usually, the cache check and bus
check target identifiers have the same address.   On Montecito the
cache check and bus check target identifiers can be different if 
a corrected error (ie SBE or unconsumed poison data) was encountered and
then an uncorrected error (ie DBE) was consumed.  In that case, the 
cache check target identifier is the physical address of the DBE (that
caused the MCA to surface) while the bus check target identifier is the 
physical address of the SBE.  This patch correctly finds the target
identifier that triggered the MCA.

If there are multiple valid cache target identifiers in the same
error record then use the one with the lowest cache level.

Signed-off-by: Russ Anderson <(rja@sgi.com)>
Signed-off-by: Tony Luck <tony.luck@intel.com>