apm821xx: Merge the Cisco Meraki MX60 & MX60W

Both of these boards share the same DTS, and hardware. The only
difference would be the PCI-E slot, and ath9k card found on the MX60W.
Due to the similarities, it would be more efficient to merge these
profiles.

Signed-off-by: Chris Blake <chrisrblake93@gmail.com>