watchdog: sa1100: make variable sa1100dog_driver static

This symbol is not used outside of sa1100_wdt.c, so marks it static.

Fixes the following warning:

>> drivers/watchdog/sa1100_wdt.c:241:24: sparse: sparse: symbol 'sa1100dog_driver'
was not declared. Should it be static?
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: sunliming <sunliming@kylinos.cn>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220802020819.1226454-1-sunliming@kylinos.cnSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/sa1100_wdt.c

@@ -238,7 +238,7 @@ static int sa1100dog_remove(struct platform_device *pdev)
 	return 0;
 }
 
-struct platform_driver sa1100dog_driver = {
+static struct platform_driver sa1100dog_driver = {
 	.driver.name = "sa1100_wdt",
 	.probe	  = sa1100dog_probe,
 	.remove	  = sa1100dog_remove,