staging: rtl8192u: remove unecessary variable

This patch removes unncessary variable in file r8192U_core.c
using Coccinelle. Semantic patch for this is as follows :
@@
identifier ret;
@@

-int ret = 0;
 ... when != ret
     when strict
-return ret;
+return 0;

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>