realtek: rename hpe,1920-8g-poe to match hardware

realtek: rename hpe,1920-8g-poe to match hardware

There are two hardware models of the HPE 1920-8g-poe switch. The version
currently in the repository is the model with a PoE budget of 180W. In
preparation of the addition of the 65W model, the existing model is
renamed to clarify the hardware version it targets.

As suggested by Pawel, the 'SUPPORTED_DEVICES' includes the old target
name to enable an upgrade path of builds with the old name.

Suggested-by: Pawel Dembicki <paweldembicki@gmail.com>
Signed-off-by: Kevin Jilissen <info@kevinjilissen.nl>