selftest/powerpc: Wrong PMC initialized in pmc56_overflow test

Test uses PMC2 to count the event. But PMC1 is being initialized.
Patch to fix it.

Fixes: 3752e453 ('selftests/powerpc: Add tests of PMU EBBs')
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/pmu/ebb/pmc56_overflow_test.c

@@ -66,7 +66,7 @@ int pmc56_overflow(void)
 
 	FAIL_IF(ebb_event_enable(&event));
 
-	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
+	mtspr(SPRN_PMC2, pmc_sample_period(sample_period));
 	mtspr(SPRN_PMC5, 0);
 	mtspr(SPRN_PMC6, 0);