In current driver, everytime we need to access the rng clock
,ie to enable or disable it, a call to clk_get is done.

This is not correct and the preferred way is to provide a rng data structure
that could be used for accessing rng resources.
Acked-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>