drm/i915: Treat crtc->mode.clock == 0 as disabled
drm/i915: Treat crtc->mode.clock == 0 as disabled

Prevent a divide-by-zero by consistently treating an 'active' CRTC
without a mode set as actually disabled.

This looks to have been first introduced with

commit 24929352481f085c5f85d4d4cbc919ddf106d381
Author: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Date:   Mon Jul 2 20:28:59 2012 +0200

    drm/i915: read out the modeset hw state at load and resume time

but then combined with

commit b0a2658acb5bf9ca86b4aab011b7106de3af0add
Author: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Date:   Tue Dec 18 09:37:54 2012 +0100

    drm/i915: don't disable disconnected outputs

it finally started oopsing.

Signed-off-by: Chris Wilson <711c73f64afdce07b7e38039a96d2224209e9a6c@chris-wilson.co.uk>
Reported-and-tested-by: Alexey Zaytsev <43b0a921664df383e302df6eeed708d7970dfdbf@gmail.com>
Tested-by: Sedat Dilek <4946ef7dd8f3b21b6f8e2f51ee1d2e36059c35a6@gmail.com>
Cc: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Cc: Jesse Barnes <bc7add126c2dbb8382bf1c28ac262b9363a32706@virtuousgeek.org>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs