logd: auditd remove logDmesg method

- logDmesg method consumes considerable memory
  resources (typically 128KB depending on kernel)
- In the future (eg: klogd, syslogd) there may be need to
  feed multiple logs or threads with the retrieved data.
- By moving the actions of logDmesg into the mainline that
  instantiates the thread objects, we can leverage a single
  allocation of the the kernel log allocation.
- logDmesg (private) is replaced with log (public) which
  has a more useful and descriptive purpose for the class.

Change-Id: Ie2dd0370661493c1e596a7e486904a0e8caab9ff