boards: deprecated: Update PHYTEC phyBOARD-Lyra AM62x

The PHYTEC phyboard_lyra_am62x board was renamed to phyboard_lyra
to simplify the board name.

The PHYTEC phycore_am62x board was renamed and moved into
phyboard_lyra as phyboard_lyra/am6234/a53.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>