ARM: at91: rm9200: remake the BGA as default version

Make BGA as the default version as we are supposed to just have
to specify when we use the PQFP version.

Issue was existing since commit:
3e90772f (ARM: at91: fix at91rm9200 soc subtype handling).

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: stable <stable@vger.kernel.org> [v3.3]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>