bridge-utils: fix the no brctl error when enable multilib

update-alternatives.bbclass does not create the brctl symbolic links for
multilib, since the wrong use of PN generates
/usr/sbin/brctl.lib32-bridge-utils, not /usr/sbin/brctl.bridge-utils;

In fact, no need to rename brctl by calling mv, since update-alternatives
will handle it

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Joe MacDonald <joe@deserted.net>