x86: mce cleanup for both Intel and AMD mce logic

x86: mce cleanup for both Intel and AMD mce logic

c/s 22964 fixed a mce memory leaks bug which may trigger xen crash
when cpu online.  However, there are 2 mce memory leaks: 1 at mce
level (arch independent), 1 at mce_intel level (arch dependent).  At
c/s 22964, it free both leaks at mce_intel level, which would has
problem under AMD arch.

This patch fix this issue.

It alloc/free poll_bankmask (arch independent) at mce level,=20 and
add a notifier block at mce level to avoid xmalloc risk when irq
disable.

With this patch, both Intel and AMD mce works OK in a clean way.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>