watchdog: core: Fix devres_alloc() allocation size

Coverity reports:

Passing argument 152UL /* sizeof (*wdd) */ to function __devres_alloc_node
and then casting the return value to struct watchdog_device ** is
suspicious.

Allocation size needs to be sizeof(*rcwdd), not sizeof(*wdd).

Fixes: 83fbae5a148c ("watchdog: Add a device managed API for ...")
Cc: Neil Armstrong <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Acked-by: Neil Armstrong <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/watchdog_core.c

···
 	struct watchdog_device **rcwdd;
 	int ret;
 
-	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*wdd),
+	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
 			     GFP_KERNEL);
 	if (!rcwdd)
 		return -ENOMEM;