ARM: shmobile: Initial r8a7790 Lager board support

Lager base board support making use of 2 GiB of memory,
the r8a7790 SoC with the SCIF0 serial port and CA15 with
ARM architected timer.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>