mt76x0: add ieee80211_ops ops pointer to mt76x0_alloc_device signature

Add ieee80211_ops ops pointer to mt76x0_alloc_device routine signature
in order to specify mac80211 callbacks and remove usb dependency from
mt76x0 generic code.
Move mt76x0_ops callbacks in usb module in order to remove leftover
usb dependency in mt76x0 generic code.
Introduce mt76x0e_ops mac80211 callbacks for pci code

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>