SPI Flash SCLK for 5A-75B V8.0

[mikeboers]

Howdy.

After an investigation, I have concluded that there is no user accessible pin connected to the flash SCLK. Instead, you can use the USRMCLK primitive. This worked for me:

spiclk (
    .USRMCLKI(clock_i),
    .USRMCLKTS(0)
);

[david-sawatzke]

FYI: Looking at litex-boards, this seems to be the same for v6.1 and v7