staging: r8188eu: Remove unreachable code in core/rtw_br_ext.c

In this file, a "return -1" immediately follows a "return 0". Remove the
second line.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>