wifi: mt76: move napi_enable() from under BH

wifi: mt76: move napi_enable() from under BH

mt76 does a lot of:

  local_bh_disable();
  napi_enable(...napi);
  napi_schedule(...napi);
  local_bh_enable();

local_bh_disable() is not a real lock, its most likely taken
because napi_schedule() requires that we invoke softirqs at
some point. napi_enable() needs to take a mutex, so move it
from under the BH protection.

Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/dcfd56bc-de32-4b11-9e19-d8bd1543745d@stanley.mountain
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250124031841.1179756-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>