dma: mv_xor: remove hw_id field from platform_data

There is no need for the platform_data to give this ID, it is simply
the channel number, so we can compute it inside the driver when
registering the channels.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

include/linux/platform_data/dma-mv_xor.h

@@ -13,7 +13,6 @@
 #define MV_XOR_NAME	"mv_xor"
 
 struct mv_xor_channel_data {
-	int				hw_id;
 	dma_cap_mask_t			cap_mask;
 	size_t				pool_size;
 };