staging: brcm80211: removed comment in rx status processing

Code cleanup. The comment is hinting that we should sanity check the
header to verify that if it claims its from a 5Ghz channel, that the
chip actually supports 5 Ghz. This is redundant (2.4G only chips do
not report 5G channels) and thus the comment was removed.

Signed-off-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>