mediatek: mt76: eeprom: fix missing of_node_put() in mt76_find_power_limits_node()

mediatek: mt76: eeprom: fix missing of_node_put() in mt76_find_power_limits_node()

BugLink: https://bugs.launchpad.net/bugs/1990162
[ Upstream commit 3bd53ea02d77917c2314ec7be9e2d05be22f87d3 ]

We should use of_node_put() for the reference 'np' returned by
of_get_child_by_name() which will increase the refcount.

Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT")
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>