target/xtensa: tests: run tests with icount

Timer tests expect certain determinism in CCOUNT updates and timer
interrupts firing. Run QEMU with -icount to get deterministic results.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

tests/tcg/xtensa/Makefile

@@ -5,7 +5,7 @@ CROSS=xtensa-$(CORE)-elf-
 
 ifndef XT
 SIM = ../../../xtensa-softmmu/qemu-system-xtensa
-SIMFLAGS = -M sim -cpu $(CORE) -nographic -semihosting $(EXTFLAGS) -kernel
+SIMFLAGS = -M sim -cpu $(CORE) -nographic -semihosting -icount 7 $(EXTFLAGS) -kernel
 SIMDEBUG = -s -S
 else
 SIM = xt-run