We've split Qualcomm MSM support into legacy and multiplatform.  The RNG
driver is only relevant on the multiplatform supported SoCs so switch the
Kconfig depends to ARCH_QCOM.
Acked-by: NHerbert Xu <herbert@gondor.apana.org.au>
CC: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: NKumar Gala <galak@codeaurora.org>