drm/i915: release struct_mutex on the i915_gem_init_hw fail path
drm/i915: release struct_mutex on the i915_gem_init_hw fail path

Release struct_mutex if init_rings() fails.

This is a regression introduced in
commit 35a57ffbb10840af219eeaf64718434242bb7c76
Author: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Date:   Thu Nov 20 00:33:07 2014 +0100

    drm/i915: Only init engines once

Reported-by: Wei Yongjun <b8f9cab8be13de37b9588aedad10a20fc3a68783@trendmicro.com.cn>
Signed-off-by: Jani Nikula <ba783f3beccaedfda693f41a15407d612a629408@intel.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

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