boards: arm: Add AM62x M4F phyBOARD-Lyra

This is a copy of the TI AM62x SK EVM board file to support the
M4F on the phyBOARD-Lyra AM62x, which is PHYTEC's development kit
for the phyCORE-AM62x SoM.

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