staging: brcm80211: removed synchronisation of wlc->machwcap field

- removed copying field wlc->machwcap from brcms_hardware to brcms_c_info
  during module attach.
- field wlc->machwcap was written but never read. Therefore it was removed.

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