crypto: picoxcell - Use of_match_ptr() macro

This eliminates having an #ifdef returning NULL for the case
when OF is disabled.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>