mt76: move rate_txpower handler in mt76 debugfs

Move rate_txpower handler in mt76 debugfs in order to be reused
in mt76x0 driver and remove duplicated code

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