ARM: ux500: consolidate base platform files

The cpu.c and cache-l2x0.c files hold only two or three simple
functions each, and they are all called from the machine
descriptors, so we can just move them all into the same file
for simplicity and consistency.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>