watchdog: jz4780: Allow selection of jz4740-wdt driver

This driver works for jz4740 & jz4780.

Suggested-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: linux-mips@linux-mips.org
Cc: linux-watchdog@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17251/


Signed-off-by: James Hogan <jhogan@kernel.org>