module: Handle 'struct module_version_attribute' as const

The structure is always read-only due to its placement in the read-only
section __modver. Reflect this at its usage sites.
Also prepare for the const handling of 'struct module_attribute' itself.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Link: https://lore.kernel.org/r/20241216-sysfs-const-attr-module-v1-2-3790b53e0abf@weissschuh.net


Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>