ARM: Use generic clkdev.h header

Get rid of the clkdev.h file in the ARM port and use the generic
one because we've gotten rid of all the machine specific
mach/clkdev.h files.

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