target/arm: make HV_EXIT_REASON_CANCELED leave hvf_arch_vcpu_exec

Without this we can spin tightly in the main HVF dispatch loop and
never release the lock long enough. As a result the HMP never gets to
run and shutting down the system deadlocks.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3228
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20251209092459.1058313-4-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

target/arm/hvf/hvf.c

@@ -2020,6 +2020,7 @@ static int hvf_handle_vmexit(CPUState *cpu, hv_vcpu_exit_t *exit)
         break;
     case HV_EXIT_REASON_CANCELED:
         /* we got kicked, no exit to process */
+        ret = -1;
         break;
     default:
         g_assert_not_reached();