drm/nouveau: fix another lock unbalance in nouveau_crtc_page_flip
drm/nouveau: fix another lock unbalance in nouveau_crtc_page_flip

Fixes a regression introduced by 060810d7abaabca "drm/nouveau: fix locking
issues in page flipping paths".  chan->cli->mutex is unlocked a second time
in the fail_unreserve path, fix this by moving mutex_unlock down.

Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org # v3.11+
Signed-off-by: Maarten Lankhorst <743c2818a341d71b99ed2b566f9f80c2fc288f93@canonical.com>
Signed-off-by: Ben Skeggs <d9f27fb07c1e9f131223ad827fa5179f3846c30b@redhat.com>

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