dt-bindings: soc: ti: Move ti,j721e-system-controller.yaml to soc/ti

dt-bindings: soc: ti: Move ti,j721e-system-controller.yaml to soc/ti

soc/ti is the more appropriate location for the system controller
device tree binding documentation so move there.

Update Kishon's email address to a working one.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20240520-for-v6-11-j721e-syscon-v1-1-f57a93e12cad@kernel.org
Signed-off-by: Nishanth Menon <nm@ti.com>