arm: Add ARCH_RANDOM Kconfig

Some boards may support architecture generated random numbers. Add
the appropriate Kconfig.

Change-Id: I0077a982c9bb6d3a35435cc27fe40b7e0596ca84
CRs-Fixed: 498392
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Linux 3.4.78

Change-Id: I830d73422b9b0878c3b5e591ab0fef08045684eb
always use short version for kernel formatting

Change-Id: I01c941c553a6dcb1d33013445576ba2d2409afd8