EDAC: Constify attribute_group structures

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with
const attribute_group. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
CC: linux-edac@vger.kernel.org
Link: http://lkml.kernel.org/r/776cb8265509054abd01b0b551624cc0da3b88e7.1499078335.git.arvind.yadav.cs@gmail.com


Signed-off-by: Borislav Petkov <bp@suse.de>