ARM: initial support for Conexant Digicolor CX92755 SoC

Add initial support for the Conexant CX92755 SoC. The CX92755 is one of the
Digicolor series of SoCs, all sharing many of the same peripherals. The code
was tested on the CX92755 evaluation kit, AKA Equinox.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Olof Johansson <olof@lixom.net>