Add the missing clk_disable_unprepare() before return in
cctrng_resume().

Fixes: a583ed31 ("hwrng: cctrng - introduce Arm CryptoCell driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>