arm64: dts: Add AMD Pensando Elba SoC support

Add AMD Pensando common and Elba SoC specific device nodes

Signed-off-by: Brad Larson <blarson@amd.com>
Link: https://lore.kernel.org/r/20230925195610.47971-5-blarson@amd.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>