watchdog: xilinx_wwdt: Calculate max_hw_heartbeat_ms using clock frequency

watchdog: xilinx_wwdt: Calculate max_hw_heartbeat_ms using clock frequency

In the current implementation, the value of max_hw_heartbeat_ms is set
to the timeout period expressed in milliseconds and fails to verify if
the close window percentage exceeds the maximum value that the hardware
supports.

1. Calculate max_hw_heartbeat_ms based on input clock frequency.
2. Update frequency check to require a minimum frequency of 1Mhz.
3. Limit the close and open window percent to hardware supported value
to avoid truncation.
4. If the user input timeout exceeds the maximum timeout supported, use
only open window and the framework supports the higher timeouts.

Fixes: 12984cea1b8c ("watchdog: xilinx_wwdt: Add Versal window watchdog support")
Signed-off-by: Harini T <harini.t@amd.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240913113230.1939373-1-harini.t@amd.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>