aspeed: Update ast2500 SoC DTS file to Linux v4.17-rc6 level

aspeed: Update ast2500 SoC DTS file to Linux v4.17-rc6 level

This is a large update of the AST2500 SoC DTS file bringing it to the
level of commit 927c2fc2db19 :

    Author:  Joel Stanley <joel@jms.id.au>
    Date:    Sat Jun 2 01:18:53 2018 -0700

         ARM: dts: aspeed: Fix hwrng register address

There are some differences on the compatibility property names. scu,
reset and clock drivers are also different.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>