mmc: atmel-mci: AP700x PDC is not connected to MCI

Earlier, atmel-mci was adapted to make use of the peripheral DMA
controller (PDC), in case normal DMA wouldn't work.
( http://comments.gmane.org/gmane.linux.kernel.mmc/9403 )

This works OK on ARM platforms (AT91), but it broke the driver
for AVR32, the AP700x.  Although the MCI has PDC support, the
connection is not done for AVR chips.

This patch makes the use of PDC depend on !CONFIG_AVR32.

Signed-off-by: Hein Tibosch <hein_tibosch@yahoo.es>
Signed-off-by: Chris Ball <cjb@laptop.org>