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>
diff --git a/doc/board/qualcomm/index.rst b/doc/board/qualcomm/index.rst
index 10b9821..0f9c429 100644
--- a/doc/board/qualcomm/index.rst
+++ b/doc/board/qualcomm/index.rst
@@ -8,3 +8,4 @@
 
    dragonboard410c
    sdm845
+   qcs404