drm/i915: Remove PIPE_CONF_CHECK_I_ALT

And move the comment to the right macro. This was mixed up in

commit cfb23ed6
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Tue Jul 14 12:17:40 2015 +0200

    drm/i915: Allow fuzzy matching in pipe_config_compare, v2

v2: Rebase.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Stone <daniels@collabora.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330476-32453-1-git-send-email-daniel.vetter@ffwll.ch