crypto: img-hash - log a successful probe

Currently the probe function only emits an output on success
when debug is specifically enabled. It would be more useful
if this happens by default.

Signed-off-by: James Hartley <james.hartley@imgtec.com>
Reviewed-by: Will Thomas <will.thomas@imgtec.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>