wifi: iwlwifi: remove async command callback

wifi: iwlwifi: remove async command callback

There's only one user of this code, which is STA unblock
during sleep for uAPSD on really old devices. Instead of
having this all through the API with calls up and down,
just implemented a special-case CMD_BLOCK_TXQS flag for
this, it's only needed in the old gen1 transport.

While at it, fix a complain that lockdep would have, as
we lock the cmd queue and then the TXQs in the reclaim
by using spin_lock_nested(). We no longer need to disable
BHs in iwl_trans_pcie_block_txq_ptrs() since it's called
with them disabled already.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231207044813.2bd95e0570fc.I16486dbc82570d2f73a585872f5394698627310d@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>