ARM: mach-shmobile: Kota2 SCIFA4 and SCIFB support

Add SCIFA4 and SCIFB support to the Kota2 board.
Only pins are configured since the SCIF platform
devices are already present in the sh73a0 code.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>