drm_hwcomposer: Replace LOG_TAG with drmhwc
It's a pain to use logcat filters for drm_hwcomposer since each file has a different tag necessitating one to specify each tag for the logcat filter or use a regex.
Use one tag for all of drm_hwcomposer to simplify this.
Signed-off-by: Sean Paul seanpaul@chromium.org