mtd: ATMEL, AVR32: inline nand partition table access

Currently atmel_nand driver used by AT91 and AVR32 calls a special callback
which return nand partition table and number of partitions. However in all
boards this callback returns just static data. So drop this callback and
make atmel_nand use partition table provided statically via platform_data.

Nicolas Ferre: I am in favor for a mainline inclusion through linux-mtd tree.
Hans-Christian Egtvedt: I'm fine by sending the changes for AVR32 through linux-mtd

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>