drm/i915/audio: HDMI audio gets the TMDS clock by crtc_clock

HDMI audio should use crtc_clock to get the TMDS clock.

This patch renames mode to adjusted_mode to unify the name.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Libin Yang <libin.yang@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/8945ac6bdae9c63a563bdd60b44dd316254e4752.1476111629.git.jani.nikula@intel.com