Bluetooth: Check if we really are in WAIT_F when F bit comes

F-bit set should be processed only if we are in the WAIT_F state.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>