Enable three DSPI flash memories on board.

Commands:
=> sf probe 1:0
SF: Detected N25Q128A with page size 256 Bytes,
erase size 64 KiB, total 16 MiB
=> sf probe 1:1
SF: Detected SST25WF040B with page size 256 Bytes,
erase size 4 KiB, total 512 KiB
=> sf probe 1:2
SF: Detected EN25S64 with page size 256 Bytes,
erase size 64 KiB, total 8 MiB

Signed-off-by: Gong Qianyu
Reviewed-by: York Sun