qtnfmac: get rid of QTNF_STATE_AP_START flag

QTNF_STATE_AP_START usage is redundant and imposes additional state
synchronization maintenance. We may as well leave state checking
to network card and upper layers (cfg80211, nl80211 and userspace).

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>