comedi: Adjust range_table_list allocation type

comedi: Adjust range_table_list allocation type

In preparation for making the kmalloc family of allocators type aware,
we need to make sure that the returned type from the allocation matches
the type of the variable being assigned. (Before, the allocator would
always return "void *", which can be implicitly cast to any pointer type.)

The returned type is "struct comedi_lrange **", but the assigned type,
while technically matching, is const qualified. Since there is no general
way to remove const qualifiers, switch the returned type to match the
assign type. No change in allocation size results.

Link: https://patch.msgid.link/20250426061015.work.971-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>