cppcheck: return value always 0

Identical condition and return expression 'rc', return value is
always 0.

Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11508

module/os/linux/spl/spl-kstat.c

@@ -486,7 +486,7 @@ proc_kstat_open(struct inode *inode, struct file *filp)
 	f = filp->private_data;
 	f->private = PDE_DATA(inode);
 
-	return (rc);
+	return (0);
 }
 
 static ssize_t