watchdog: ftwdt010_wdt: fix test for platform_get_irq() failure

This code assumes that platform_get_irq() function returns zero on
failure.  In fact, platform_get_irq() never returns zero.  It returns
negative error codes or positive non-zero values on success.

Fixes: eca10ae6

 ("watchdog: add driver for Cortina Gemini watchdog")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/YvTgRk/ABp62/hNA@kili


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>