AVR32-pio: Use seq_putc() in pio_bank_show()

A single character (line break) should be put into a sequence.
Thus use the corresponding function "seq_putc".

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

arch/avr32/mach-at32ap/pio.c

@@ -373,7 +373,7 @@ static void pio_bank_show(struct seq_file *s, struct gpio_chip *chip)
 		if (imr & mask)
 			seq_printf(s, " irq-%d edge-both",
 				gpio_to_irq(chip->base + i));
-		seq_printf(s, "\n");
+		seq_putc(s, '\n');
 	}
 }