ARM: integrator: drop EBI access use syscon

The EBI lookup is not longer in use: this has been moved to the
NAND chip driver. The syscon node is better accessed indirectly
using the regmap like the NAND chip driver does, so let's use
the syscon to set the modem control signals RTS/CTS through the
dedicated syscon register.

We also migrate the decoder status "SC_DEC" register that
enumerate the logic modules using syscon.

Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>