X86_64: Pass 'hidden method index' in EAX

Method* is in EDI, and EAX isn't an argument register, so EAX is free
to hold the hidden method index.

Change-Id: I793a54d00a4593e140f97144419d849b53bfdf44
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>
3 files changed