hwrng: bcm2835 - Add missing clk_disable_unprepare in bcm2835_rng_init

commit d57e2f7c upstream.

Add the missing clk_disable_unprepare() before return in
bcm2835_rng_init().

Fixes: e5f9f41d ("hwrng: bcm2835 - add reset support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>