staging: brcm80211: remove useless bcm_ether_ntoa()

Since we have '%pM' modifier in the kernel's *printf() we don't need to
convert address to the string beforehand.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Nohee Ko <noheek@broadcom.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: linux-wireless@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>