APEI: Fix WHEA _OSC call

Bit 0 of the support parameter to the OSC call should be set in order to
indicate that the OS supports the WHEA mechanism. Stuart Hayes tracked
an APEI issue on some Dell platforms down to this.

Reported-by: Stuart Hayes <Stuart_Hayes@Dell.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>