drm/i915/audio: remove misleading checks for !eld[0]

We'll never end up in the hooks with eld[0] unset, as that's checked by
drm_select_eld().

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>