ARM: shmobile: r7s72100 SCIF support

Add SCIF serial port support to the r7s72100 SoC by
adding platform devices for SCIF0 -> SCIF7 together with
clock bindings. DT device description is excluded at
this point since such bindings are still under
development.

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