This reverts commit 39314361, which
was commit f05bb0c7 upstream.

This has been found to cause GPU hangs when backported to 3.2, though
not in mainline.

References: http://bugs.launchpad.net/bugs/1140716
Cc: Steve Conklin <sconklin@canonical.com>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: Bradd Figg <brad.figg@canonical.com>
Cc: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>