ARM: plat-nomadik: timer: Export reset functions

We make the reset function from the driver public, then
we also move of all register defines from the public header
file into driver, where they belong.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>