drm/cec: Add CEC over Aux register definitions

Adding DPCD register definitions from the DP 1.3 specification for CEC
over AUX support.

V2: Add DP_ prefix to all defines.
V3: missed prefixes from the ESI1 defines.

Cc: Jani Nikula <jani.nikula@linux.intel.com>.

Change-Id: Ie4a1de4a96cea07061622f3300a5cf9d9782ddcf
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1492703263-11494-1-git-send-email-clinton.a.taylor@intel.com
Git-commit: d753e41d475421543eaaea5f0feadba827f5fa01
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[vvalluru@codeaurora.org: resolved merge conflicts]
Signed-off-by: Venkata Prahlad Valluru <vvalluru@codeaurora.org>
Signed-off-by: Chirag Khurana <ckhurana@codeaurora.org>