staging: brcm80211: remove brcmfmac interface name override

The brcmfmac had a module parameter which could be used to override
the name of the wireless net device name and it defaults to 'wlan'.
This is considered rather useless, because what is in a name.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>