dt-bindings: arm: ti: Add binding for Siemens IOT2050 M.2 variant

This new variant is derived from the Advanced PG2 board, replacing the
MiniPCI slot with B and E-keyed M.2 slots.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/e49b4451b6c85ba28bdbbe42b25d9eeecebbe2d7.1674110442.git.jan.kiszka@siemens.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>