ath10k: remove excessive rx msdu len check

This throw a lot of pointless warnings in case of DFS (radar
detection) and PHYERR events from firmware, when firmware may
actually insert more data, than we assume.

Besides of being noisy this debug does not protect or check
anything usefull currently. It was introduced long time ago
while debugging aggregations. So just removing it.

Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>