MAINTAINERS: fix Andreas Bießmann AVR32 entry

The grasshopper board is a avr32 based device and belongs therefore to the avr32
section.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index fbd1c0f..fc4c919 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -618,7 +618,6 @@
 Andreas Bießmann <andreas.devel@gmail.com>
 
 	at91rm9200ek	at91rm9200
-	grasshopper	avr32
 
 Cliff Brake <cliff.brake@gmail.com>
 
@@ -1091,6 +1090,9 @@
 #	Board		CPU						#
 #########################################################################
 
+Andreas Bießmann <andreas.devel@googlemail.com>
+	grasshopper		AT32AP7000
+
 Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
 
 	FAVR-32-EZKIT		AT32AP7000