platform/chrome: Constify static attribute_group structs

The only usage of these is to print their name in a dev_err-message, and
to pass their address to sysfs_create_group() and sysfs_remove_group(),
both which takes pointers to const. Make them const to allow the compiler
to put them in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210109001748.58036-1-rikard.falkeborn@gmail.com