fixing dmi match for hp t5745 and hp st5747 thin client

commit 62004978df3898649e152751eb6ac264a323ec36 upstream.

Match the correct information which is DMI_PRODUCT_NAME instead of DMI_BOARD_NAME
See dmidecode information on launchpad for both thin client:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/911920
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/911916

Signed-off-by: Marc Gariepy <mgariepy@ubuntu.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>