ARM: 6137/1: nomadik hwrng: Add clock support

This adds the clock support to the Nomadik RNG driver

Signed-off-by: srinidhi kasagar <srinidhi.kasagar@stericsson.com>
Acked-by: Linus walleij <linus.walleij@stericsson.com>
Acked-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>