art_quick_lock_object uses registers incorrectly

x86 implementation of art_quick_lock_object uses registers
incorrectly in the case of .Lalready_thin. eax points to object
while it is used as holding the lock word.

The patch fixes this.

Change-Id: Iacf1a40c6570fae78a5504ca3b2f1218631f7a8f
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>