hwrng: core - Move hwrng_init call into set_current_rng

We always do hwrng_init in set_current_rng.  In fact, our current
reference count system relies on this.  So make this explicit by
moving hwrng_init into set_current_rng.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --cc drivers/char/hw_random/core.c
Simple merge