Simply replace the linear search with the kernel's binary
search implementation. There is only six registers currently
in that table so this may not be that interesting. It adds a
function call so hopefully remains performance neutral for now.

v2: No need for manual conversion to bool for return.
    (Joonas Lahtinen)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>