dt-bindings: vendor-prefixes: Add entry for Aldec

Per their website:
Aldec, Inc. is an industry-leading Electronic Design Automation (EDA)
company delivering innovative design creation, simulation and
verification solutions to assist in the development of complex FPGA,
ASIC, SoC and embedded system designs.

Link: https://www.aldec.com/


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>