drm/i915: Removed unused vm args

i915_gem_execbuffer_relocate became defunct in:
commit 27173f1f
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Wed Aug 14 11:38:36 2013 +0200

    drm/i915: Convert execbuf code to use vmas

eb_create: never used?

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: The lingering vm parameter to eb_create might have been back
from the days where we didn't yet keep both vmas and obj lists in the
eb struct. But I didn't check really.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>