"adapter->sleep_cfm" is always non-NULL at this point.  Static checkers
complain that we already dereference it at the start of the function
when we do:

	skb_put(adapter->sleep_cfm, sizeof(struct mwifiex_opt_sleep_confirm));
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>