zynq: Generate node for a9-global-timer

Also support cases where a9-global-timer wasn't exported
by tools.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
arm: Generate clock and operating-points

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Fix i2c compat string generation

xlnx,zynq-i2c-1.00.a has never been used in our tree
just for developing. Use cadence compat string instead.

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