vmx: Remove unused expensive functions

vmx: Remove unused expensive functions

Now that we replaced the expensive functions with better performing
alternatives, we should remove them so they will not be used again.

Running Cairo benchmark on trimmed traces gave the following results:

POWER8, 8 cores, 3.4GHz, RHEL 7.2 ppc64le.

Speedups
========
t-firefox-scrolling     1232.30 -> 1096.55 :  1.12x
t-gnome-terminal-vim    613.86  -> 553.10  :  1.11x
t-evolution             405.54  -> 371.02  :  1.09x
t-firefox-talos-gfx     919.31  -> 862.27  :  1.07x
t-gvim                  653.02  -> 616.85  :  1.06x
t-firefox-canvas-alpha  941.29  -> 890.42  :  1.06x

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>