arcmsr: add const to bin_attribute structures

Add const to bin_attribute structures as they are only passed to the
functions system_{remove/create}_bin_file. The arguments passed are of
type const, so declare the structures to be const.

Done using Coccinelle.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>