powerpc/axonram: Enable partitioning of the Axons DDR2 DIMMs

DDR2 memory DIMMs on the Axon could be accessed only as one partition
when using file system drivers which are using the direct_access() method.
This patch enables for such file system drivers to access Axon's DDR2 memory
even if it is splitted in several partitions.

Signed-off-by: Maxim Shchetynin <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

arch/powerpc/sysdev/axonram.c

···
 	struct axon_ram_bank *bank = device->bd_disk->private_data;
 	loff_t offset;
 
-	offset = sector << AXON_RAM_SECTOR_SHIFT;
+	offset = sector;
+	if (device->bd_part != NULL)
+		offset += device->bd_part->start_sect;
+	offset <<= AXON_RAM_SECTOR_SHIFT;
 	if (offset >= bank->size) {
 		dev_err(&bank->device->dev, "Access outside of address space\n");
 		return -ERANGE;