ideapad-laptop: add alternative representation for Yoga 2 to DMI table

There is at least one (mine) Yoga 2 Pro in existence that has incorrect
product version stored in DMI (reading as "INVALID"), causing it to not be
recognized as Yoga 2 by ideapad-laptop module, which in turn causes
non-existent hardware rfkills to be always reported as blocked.

This change adds a second check by board name, which is "Yoga2".
Looks like it also happens to be "INVALID" on some other Yoga 2 machines
where product version is correct instead, so the original check is left
intact to catch both cases.

Signed-off-by: Sebastian Krzyszkowiak <dos@dosowisko.net>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>