sim/testsuite/cris/hw/rv-n-cris/irq1.ms: Disable due to randomness

For reasons that remain largely to be investigated (besides
the apparent lack of synchronization between two processes),
this test fails randomly, with two different sets of common
outputs.  Curiously, that doesn't happen for the other
similar tests.  There's a comment that mentions this, though
that doesn't make it a sustainable part of a test-suite.
(Known-blinking tests should be disabled until fixed.)

sim/testsuite/cris:
	* hw/rv-n-cris/irq1.ms: Disable by use of a never-matched
	"progos" value.