gsyncd / geo-rep: use the correct virtual xattr to collect 'gfid'

Change-Id: Ifea32ad1b2695f1668428fae6b263014bf320b70
BUG: 996379
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/5589
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>