staging: r8188eu: Directly return _SUCCESS instead of using local ret variable

staging: r8188eu: Directly return _SUCCESS instead of using local ret variable

As init_mlme_ext_priv function always returns SUCCESS , We can change
return type from int to void.

fixes coccinelle warning:
./drivers/staging/r8188eu/core/rtw_mlme_ext.c:357:5-8: Unneeded variable: "res".
 Return "_SUCCESS" on line 380

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Link: https://lore.kernel.org/r/1648603740-14760-1-git-send-email-baihaowen@meizu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>