drm/msm: Don't bail out when debugfs creation fails

There's no reason why the absence of debugfs should cause the GPU driver
to break. Fix it.

Change-Id: I3c7e8ba241e154e4cc7d1338ffeef42a66347593
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>