selftests/powerpc: Skip L3 bank test on older CPUs

This is a test of specific piece of logic in isa207-common.c, which is
only used on Power8 or later. So skip it on older CPUs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015727.1977134-7-mpe@ellerman.id.au

tools/testing/selftests/powerpc/pmu/l3_bank_test.c

@@ -20,6 +20,9 @@ static int l3_bank_test(void)
 	char *p;
 	int i;
 
+	// The L3 bank logic is only used on Power8 or later
+	SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_2_07));
+
 	p = malloc(MALLOC_SIZE);
 	FAIL_IF(!p);