HID: bpf: rework hid_bpf_ops_btf_struct_access

The idea is to provide a list of stucts and their editable fields.

Currently no functional changes are introduced here, we will add some
more writeable fields in the next patch.

Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20240608-hid_bpf_struct_ops-v3-15-6ac6ade58329@kernel.org


Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>