crypto: caam - enable instantiation of all RNG4 state handles

RNG4 block contains multiple (i.e. 2) state handles that can be
initialized. This patch adds the necessary code for detecting
which of the two state handles has been instantiated by another
piece of software e.g. u-boot and instantiate the other one (or
both if none was instantiated). Only the state handle(s)
instantiated by this driver will be deinstantiated when removing
the module.

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