quicklogic: qlf_k4n8: tests: disable io_reg_max
quicklogic: qlf_k4n8: tests: disable io_reg_max

Disabling io_reg_mux test because it is failing,
possibly due to update of yosys plugins in 1acdf953

Signed-off-by: Paweł Czarnecki <be3a62494a976d1435cc0900bd9adf3fa1029787@antmicro.com>

SymbiFlow/symbiflow-arch-defs,SymbiFlow/symbiflow-arch-defs