crypto: caam - uninstantiate RNG state handle 0 if instantiated by caam driver

If the caam driver module instantiates the RNG state handle 0, then
upon the removal of the module, the RNG state handle is left
initialized. This patch takes care of reverting the state of the
handle back to its previous uninstantatied state.

Signed-off-by: Alex Porosanu <alexandru.porosanu@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>