staging: rtl8712: Replace r8712_find_network()

Remove function r8712_find_network as all it does is call
_r8712_find_network.
Rename _r8712_find_network to r8712_find_network for compatibility with
call sites.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>