iwlwifi: move bc_table_dword to a common trans header

The bc_table_dword code is not directly related to the PCIe transport,
so move the structures it uses to the common iwl-trans.h header.

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.20200924162105.1e3027abd0b5.Ie9f672983796586671a4374bf6dcda846875b690@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>