arm64: dts: ti: iot2050: Add support for product generation 2 boards

This adds the devices trees for IOT2050 Product Generation 2 (PG2)
boards. We have Basic and an Advanced variants again, differing in
number of cores, RAM size, availability of eMMC and further details.
The major difference to PG1 is the used silicon revision (SR2.x on
PG2).

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/cc868da8264324bde2c87d0c01d4763e3678c706.1632657917.git.jan.kiszka@web.de