dt-bindings: watchdog: imx7ulp-wdt: Add imx93 compatible string

The wdog on i.MX93 is modified from i.MX8ULP with some changes,
it uses one compatible string, so add i.MX93 support.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220215081202.787853-1-peng.fan@oss.nxp.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>