wireless-regdb: update MX's regulatory rules

This:

  o increases the 2.4 GHz frequency range but with the
    compromise of reducing the max EIRP from 27 dBm to
    20 dBm

  o extends the second 5 GHz DFS frequency range

Source is QCA's regulatory team's efforts.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>