isisd: update struct isis_route_info has multiple sr info by algorithm

isisd: update struct isis_route_info has multiple sr info by algorithm

Before this commit, there was only one sr psid info
included in route_info.

In fact, in RFC8667, Algorithm ID, which is a property of
Prefix-SID, has 8 bits of information. That is, each Prefix
can hold up to 256 Prefix-SIDs. This commit implements it.
The previously implemented single Prefix-SID will be
continued as Algorithm 0.

Signed-off-by: Hiroki Shirokura <hiroki.shirokura@linecorp.com>
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>