wl12xx: don't check wow param on suspend/resume

Since mac80211 calls suspend/resume only when wowlan triggers
exist, there is no need to check for triggers existance in the
callbacks as well.
Add a WARN_ON() to verify it.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>