staging: rtl8723bs: use %pM format for MAC addresses

Use %pM format instead of custom printing code.

Signed-off-by: Ross Schmidt <ross.schm.dev@gmail.com>
Link: https://lore.kernel.org/r/20201105034754.12383-2-ross.schm.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
