gdb/solib-frv: move lm_info object to solib

gdb/solib-frv: move lm_info object to solib

I noticed that the lm_info_frv objects created in frv_current_sos are
never moved to the solib object.  This bug was introduced in 8971d2788e
("gdb: link so_list using intrusive_list"), which mistakenly removed the
line

    sop->lm_info = std::move (li);

... probably due so a bad merge conflict resolution.

Re-add this line.

If merged in master, I would cherry-pick this to gdb-15-branch.

Change-Id: I609a1a5ad39e93f70a95ea5ebe3f8ff4ab6a8db2
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32005
Approved-By: Andrew Burgess <aburgess@redhat.com>