Factor in clear values wherever required while updating destination
min/max.

References: HSDES#1604444184
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Cc: mesa-dev@lists.freedesktop.org
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180510200708.18097-1-michel.thierry@intel.com
Cc: stable@vger.kernel.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180514165445.9198-1-michel.thierry@intel.com
(backported from commit 0c79f9cb)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>