arm: zynq: Migrate platform to clock controller

Migrate the Zynq platform and its drivers to use the new clock
controller driver.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Mike Turquette <mturquette@linaro.org>