stm class: Remove a pointless line

No point in explicitly setting something to zero right after we
explicitly checked that it is zero. Fix this.
Reported-by: Alan Cox <alan.cox@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Laurent Fert <laurent.fert@intel.com>

drivers/hwtracing/stm/core.c

@@ -546,8 +546,6 @@ static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
 	if (ret)
 		goto err_free;
 
-	ret = 0;
-
 	if (stm->data->link)
 		ret = stm->data->link(stm->data, stmf->output.master,
 				      stmf->output.channel);