ARM: zynq: Move of_clk_init from clock driver

Move of_clk_init() from clock driver to enable
options not to use zynq clock driver.
Use for example fixed clock setting.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
ARM: zynq: Add waituart implementation

Add missing waituart implementation.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
ARM: zynq: Add support for SOC_BUS

Provide information through SOC_BUS to user space.
Silicon revision is provided through devcfg device.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>