mt76: mt7615: do not set MT76_STATE_PM at bootstrap

Remove MT76_STATE_PM in mt7615_init_device() and introduce
__mt7663s_mcu_drv_pmctrl for fw loading in mt7663s.
This patch fixes a crash at bootstrap for device (e.g. mt7622) that do
not support runtime-pm

Fixes: 7f2bc8ba

 ("mt76: connac: introduce wake counter for fw_pmctrl synchronization")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/e5a2618574007113d844874420f7855891abf167.1621085028.git.lorenzo@kernel.org