iwlwifi: fix wowlan suspend

This was broken by the commit 023ca58f
"iwlwifi: Move the core suspend function to iwl-agn-lib"
where for some reason the code changed while moving,
from
	.len[0] = sizeof(*key_data.rsc_tsc),
to
	.len[0] = sizeof(key_data.rsc_tsc),

Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>