Slave SDI is not supported

[M0stafaRady]

The controller supports SPI and SQI. However there is another mode supported by the slave memory 23LC1024 called SDI (Serial Dual Interface). The RTL have 3 modes and of them is dual but it's not behaving like the slave is expected a dual mode would behave.
The RTL dual mode starts by sending the command using only SIO0:
https://github.com/efabless/EF_PSRAM_CTRL_V2/blob/afc59c61263b9748e00f18bb968459c1cb509f30/hdl/rtl/EF_PSRAM_CTRL_V2.v#L186

However the slave expected the command to be sent over SIO0 and SIO1:
https://github.com/efabless/EF_PSRAM_CTRL_V2/blob/afc59c61263b9748e00f18bb968459c1cb509f30/verify/utb/23LC1024.v#L232-L234