* Add in a comment about ar5416InitUserSettings() potentially
modifying AR_DIAG_SW.
There's a hardware workaround which sets disabling some errors
early at startup and clears said bits before the PCU begins
receiving - it does this to avoid RX descriptor status errors.
It's possible these bits aren't being completely properly twiddled
in all instances; but in particular if the diag_reg HAL variable
is set it won't be setting these bits correctly. I'll review this
at some point.
* Disable multicast search on mac address and key id - the driver
doesn't use it at the moment and thus adhoc may be broken for
merlin and later.
* Change this to be for Merlin 1.0 (which from what I understand
wasn't ever publicly released) to be more correct.