wifi: mt76: mt7603: rework/fix rx pse hang check

It turns out that the code in mt7603_rx_pse_busy() does not detect actual
hardware hangs, it only checks for busy conditions in PSE.
A reset should only be performed if these conditions are true and if there
is no rx activity as well.
Reset the counter whenever a rx interrupt occurs. In order to also deal with
a fully loaded CPU that leaves interrupts disabled with continuous NAPI
polling, also check for pending rx interrupts in the function itself.

Fixes: c8846e10

 ("mt76: add driver for MT7603E and MT7628/7688")
Signed-off-by: Felix Fietkau <nbd@nbd.name>