board: qualcomm: Add support for QCS404 EVB

Add support for Qualcomm QCS404 SoC based evaluation board.

Features:
- Qualcomm Snapdragon QCS404 SoC
- 1GiB RAM
- 8GiB eMMC, uSD slot

U-boot is chain loaded by ABL in 64-bit mode as part of boot.img.
For detailed build and boot instructions, refer to
doc/board/qualcomm/qcs404.rst.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>