ARM: milbeaut: Add basic support for Milbeaut m10v SoC

This adds the basic M10V SoC support under arch/arm.
Since all cores are activated in the custom bootloader before booting
linux, it is necessary to wait for the secondary-cores using cpu-enable-
method and special sram.

Signed-off-by: Sugaya Taichi <sugaya.taichi@socionext.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>