crypto: talitos - remove param 'extent' in map_single_talitos_ptr()

map_single_talitos_ptr() is always called with extent == 0, so lets remove this unused parameter

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>