arm64: dts: ti: k3-am62-main: Add GPU device node [DO NOT MERGE]

Add the Series AXE GPU node to the AM62 device tree.

Changes since v5:
- Update compatible string to match marketing name

Changes since v4:
- Remove interrupt name
- Make property order consistent across dts and bindings doc
- Fixed formatting (replaced spaces with tabs)

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>