staging: mt7621-pinctrl: replace seq_printf with seq_puts

For a constant format without additional arguments, use seq_puts()
instead of seq_printf() fixing also the following checkpatch.pl
warning: 'Prefer seq_puts to seq_printf'
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c

@@ -92,7 +92,7 @@ static void rt2880_pinctrl_pin_dbg_show(struct pinctrl_dev *pctrldev,
 					struct seq_file *s,
 					unsigned int offset)
 {
-	seq_printf(s, "ralink pio");
+	seq_puts(s, "ralink pio");
 }
 
 static void rt2880_pinctrl_dt_subnode_to_map(struct pinctrl_dev *pctrldev,