Remove check that can never be true.

clang warns:
warning: comparison of constant 268435455 with expression of type
'CARD16' (aka 'unsigned short') is always false

Signed-off-by: Thomas Klausner <wiz@NetBSD.org>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>