arm64: zynqmp: Add L2 cache nodes

Describe SoC L2 cache hierarchy.

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/130e5a6acbee94809b63a61cde5450fbff88cc9c.1685964230.git.michal.simek@amd.com