iwlwifi: move command queue number out of the iwl_shared struct

The command queue number is required by the transport
layer, but it can be determined only by the op mode.
Move this parameter to the dvm op mode, and configure
the transport layer using an API.

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>