Make sure we're muxed to the SP before setting the mux to the host

[mkeeter]

I noticed that the SP hangs if you call set_mux(HostCPU) twice in a row. This is because the first call switches the mux from the SP to the host; the second call tries to read from flash while it's muxed to the host (to find the APOB, ABL0 version, etc). When the flash is muxed to the host, the FPGA never loads bytes into the SP's FIFO, so this hangs the hf task forever.

[labbott]

Was this issue always present or did the APOB version pinning make this show up?

[mkeeter]

I think it's always been present – even before APOB pinning, we'd call ApobState::init in this conditional, which reads from flash to pick the active slot.