Staging: rtl8192u: using random_ether_addr() to generate random MAC

Using random_ether_addr() to generate a random Ethernet
address (MAC) that is not multicast and has the local
assigned bit set. Not need to duplicating its implementation.

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/

)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>