msm: vidc: Enable/disbale debug messages

Adds support to enable/disable debug messages
from debugfs so that messages only upto a
desired priority can be enabled. By default,
only error messages are enabled.

Change-Id: Id133c3f109d227862d1fa580f3b5df4cbbc37e11
Signed-off-by: Blaine Dietrich <blained@codeaurora.org>
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>