drm/msm: Take the mutex before calling msm_gem_new_impl

drm/msm: Take the mutex before calling msm_gem_new_impl

[ Upstream commit 90dd57de4a043f642179b1323a31ca3ced826611 ]

Amongst its other duties, msm_gem_new_impl adds the newly created
GEM object to the shared inactive list which may also be actively
modifiying the list during submission.  All the paths to modify
the list are protected by the mutex except for the one through
msm_gem_import which can end up causing list corruption.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
[add extra WARN_ON(!mutex_is_locked(&dev->struct_mutex))]
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>