iwlwifi: default WMM AC parameters

Set the default WMM AC parameters for BK/BE/VI/VO parameters:

AC        CWmin         CW max      AIFSN      TXOP Limit    TXOP Limit
                                              (802.11b)      (802.11a/g)
AC_BK      15            1023        7           0               0
AC_BE      15            1023        3           0               0
AC_VI       7              15        2          188             94
                                              (6.016ms)       (3.008ms)
AC_VO       3               7        2          102             47
                                              (3.264ms)       (1.504ms)

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>