arm64: zynqmp: Add pwm-fan node and fix ttc0 pwm-cells property

Add pwm-fan node to control fan through hwmon and change
pwm-cells property to 3 to allow fancontrol utility to
function correctly.

Signed-off-by: Vishal Patel <vishal.patel@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/21b4dfce3e45136a468974ea3dedca03320e27b8.1652262769.git.michal.simek@amd.com