drm/i915: Remove incorrect comment about struct mutex
drm/i915: Remove incorrect comment about struct mutex

This statenment became false here:

commit 4fc688ce79772496503d22263d61b071a8fb596e
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Nov 2 11:14:01 2012 -0700

    drm/i915: protect RPS/RC6 related accesses (including PCU) with a new mutex

Signed-off-by: Ben Widawsky <73675debcd8a436be48ec22211dcf44fe0df0a64@bwidawsk.net>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs