mwifiex: ie_list is an array, so no need to check if NULL

ap_ie->ie_list is an array of struct mwifiex_ie and can never
be null, so the null check on this array is redundant and can
be removed.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>