Input: wdt87xx_i2c - replace mdelay() with msleep() in wdt87xx_resume()

wdt87xx_resume() is never called in atomic context.  It calls mdelay() to
busily wait, which is not necessary.  mdelay() can be replaced with
msleep().

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>