drm/msm: allow sde_atrace to show up on different process

Currently trace always shows up on same process as caller, add
an additional function to allow attaching trace to any process.

Change-Id: I8fc124f9d1cfae28d1868a9a3067d0e92eda934e
Signed-off-by: Adrian Salido <salidoa@google.com>
Signed-off-by: Christopher Braga <cbraga@codeaurora.org>