watchdog: xilinx: Fix driver header

- Remove reference for IP version
- Fix header coding style
- Remove notes which are visible from the code
- Fix driver license according to header

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>