ARM: shmobile: koelsch: Enable SCIF0 and SCIF1 serial ports in DT

SCIF0 and SCIF1 are used as debug serial ports. Enable them and
configure pinmuxing appropriately. We can now remove the clkdev
registration hack for SCIF devices from the Koelsch reference board
file.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
[horms+renesas@verge.net.au: added aliases to avoid device renumbering]
[horms+renesas@verge.net.au: resolved conflicts]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>