avr32: Fix typo of IFSR in a comment in the PIO header file

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/arch/avr32/mach-at32ap/pio.h b/arch/avr32/mach-at32ap/pio.h
index 7795116..9484dfc 100644
--- a/arch/avr32/mach-at32ap/pio.h
+++ b/arch/avr32/mach-at32ap/pio.h
@@ -57,7 +57,7 @@
 
 /* Bitfields in IFDR */
 
-/* Bitfields in ISFR */
+/* Bitfields in IFSR */
 
 /* Bitfields in SODR */