mt76: fix tx power issues

- tx power is stored in the channels after ieee80211_register_hw, so
  chan->orig_mpwr needs to be updated as well
- for non-TSSI devices, mt76x2e needs to use a different target power value
  from the EEPROM
- fix a rounding error in a few places (need to round up, not down)

Signed-off-by: Felix Fietkau <[email protected]>

mt7603/init.c

@@ -489,6 +489,7 @@ mt7603_init_txpower(struct mt7603_dev *dev,
 	for (i = 0; i < sband->n_channels; i++) {
 		chan = &sband->channels[i];
 		chan->max_power = target_power;
+		chan->orig_mpwr = target_power;
 	}
 }