watchdog: da9062: Add dependency on I2C

Since commit 057b52b4 ("watchdog: da9062: make restart handler atomic
safe"), the driver calls i2c functions directly. It now therefore depends
on I2C. This is a hard dependency which overrides COMPILE_TEST.

Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Fixes: 057b52b4 ("watchdog: da9062: make restart handler atomic safe")
Cc: Marco Felsch <m.felsch@pengutronix.de>
Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Cc: Stefan Lengfeld <contact@stefanchrist.eu>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>