x86 mce: fix a few possible issues

x86 mce: fix a few possible issues

Do not share synchronization variables between the trap handler and
the softirq handler, as this will cause problems. Abstract the
synchronization bits into functions. Make the synchronization code
aware of a panic, so that spinning with interrupts disabled is
avoided.

To avoid problems with MCEs happening while we're doing recovery
actions in the softirq handler, implement a deferred list of telemetry
structures, using the mctelem interfaces. Thist list will get updated
atomically, so any additional MCEs will not cause error telemetry to
be missed or not handled.

Signed-off-by: Frank van der Linden <frank.vanderlinden@sun.com>
Signed-off-by: Liping Ke <liping.ke@intel.com>
Signed-off-by: Yunhong Jiang<yunhong.jiang@intel.com>