add support for on board MTD flash of AVR32 Grasshopper board

target/avr32/kernel/grasshopper

@@ -8,3 +8,13 @@ CONFIG_SERIAL_ATMEL=y
 CONFIG_SERIAL_ATMEL_CONSOLE=y
 CONFIG_SERIAL_ATMEL_PDC=y
 CONFIG_BOARD_GRASSHOPPER_USART1=y
+CONFIG_MTD=y
+CONFIG_MTD_BLOCK=y
+CONFIG_MTD_BLKDEVS=y
+CONFIG_MTD_CFI=y
+CONFIG_MTD_CFI_INTELEXT=y
+CONFIG_MTD_CFI_AMDSTD=y
+CONFIG_MTD_CFI_STAA=y
+CONFIG_MTD_PHYSMAP=y
+CONFIG_MTD_PHYSMAP_OF=y
+CONFIG_MTD_CMDLINE_PARTS=y