I have identical problem like in Unable to enable DSPI0 (SPI1) on LS1021a .
LS1021A-TWR board, rev.1 silicon, SDK 1.8. Use default rcw & u-boot.
DSPI driver don`t register as a master on spi bus.
Also I have checked dtb using u-boot's fdt parser and everything looks like it supposed to be - "status" for "dspi0" is "okay". But after the system started i did "cat /proc/device-tree/soc/dspi@21000000/status" and got "disabled" as output.
If i use dspi1 all ok - i see that master registered and call my spi protocol driver Probe() func.
I try u-boot from SDK2.0 and DSPI0 successfully register master on SPI bus. So, there is some problem in SDK1.8.