ARM: u300: remove deps from debug macro

This rids the dependency to <mach/hardware.h> (which is an
implicit dependency to <mach/u300-regs.h>) from the U300
debug macro. Take this opportunity to update the file
header.

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