It can be understood from the data manual that SSD20X has 2 SPI interfaces, one has been used for SPI Flash, so there is only one SPI interface for developers.

If you need to open the SPI interface, you need to change the status in DTS to ok:
#vi infinity2m.dtsi

Then configure the corresponding pin as SPI_MODE:
#vi infinity2m-ssc011a-s01a-padmux-display.dtsi

Here, since SPI_MODE has been set by default, it is only necessary to ensure that it is not configured for other functions.
Finally load the MSPI driver:
#cd kernel && ARCH=arm make menuconfig