Drop the function of of_match_ptr() to fix the warning of unused variable
'starfive_wdt_match'.

Fixes: db728ea9 ("drivers: watchdog: Add StarFive Watchdog driver")
Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230427074400.55380-1-xingyu.wu@starfivetech.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>