msm: pil-msa: Fix authentication error path

Once the Q6 has booted, it is not possible to access
MSS registers. If there is an error during the auth
process, don't attempt to touch those registers.

Also, ensure that MSS_RESTART is re-asserted in the
error path as well.

Change-Id: I1e062f73f1dfdbf60c038c61f5ccd7358e81c702
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>