x86/mce Add validation check before GHES error is recorded

When GHES error record is logged into mcelog kernel buffer, a validation
check for physical address is necessary, which prevents reporting an
invalid physical address.

[Since physical address is the only useful element in this error record,
we drop generating the record completely if we don't have a valid address]

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>