Most newer targets have been converted to consistently use
vendor_model scheme for device definitions/image names, ox820 is
using it as well, so let's just convert ox810se for consistency.
While at it, use generic setup for DEVICE_DTS and add SUPPORTED_DEVICES.
The latter have been introduced for ox820 already in
cf7896117b3e ("oxnas: enable image metadata by setting SUPPORTED_DEVICES")
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
1e55df2e41