x86 mce: Clean Intel's MCE handler code

x86 mce: Clean Intel's MCE handler code

Add intel_mce_type check according to Intel's SDM.

Reduce intel_memerr_dhandler()'s indent to make code easily read. And
add a page_off action when we offline the page, so that dom0 can knows
about the action taken by xen hypervisor.

Add a default delay mce handler, which will crash if unknow SRAR error
or fatal error, otherwise, system continue.

Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>