Staging: rtl8192u: Replace random_ether_addr with eth_random_addr

The macro random_ether_addr is calling the function eth_random_addr.
Therefore, the call to random_ether_addr can be replaced with
eth_random_addr.
Remove the wrapper function ieee80211_randomize_cell and replace its
call with eth_random_addr as it is wrapping random_ether_addr.
Done using coccinelle:

@@
expression addr;
@@
- random_ether_addr(addr);
+ eth_random_addr(addr);

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>