iwlwifi: tx: move handing sync/async host command to trans

iwlwifi: tx: move handing sync/async host command to trans

Handling host commands in a sync way is not directly related to PCIe
transport, and can serve as common logic for any transport, so move
it to trans layer.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210117164916.fde99af4e0f7.I4cab95919eb35cc5bfb26d32dcf5e15419d0e0ef@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>