msm: msm_bus: Improve shell client module

Update shell client to avoid making multiple unregister
bus driver calls. Disable shell client logs also as it
can cause issue due to excessive logging.

Change-Id: Ib456bb10357a2b5cc392f13f1a1721063de55d9e
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>