fix avr32 build errors

Commit 7d2be074
(atmel-mci: Driver for Atmel on-chip MMC controllers)
causes build errors like:

<--  snip  -->

...
  CC      arch/avr32/boards/atstk1000/atstk1003.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/avr32/boards/atstk1000/atstk1003.c: In function 'atstk1003_init':
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/avr32/boards/atstk1000/atstk1003.c:157: error: too few arguments to function 'at32_add_device_mci'
make[2]: *** [arch/avr32/boards/atstk1000/atstk1003.o] Error 1

<--  snip  -->

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>