perf/x86/rapl: Fix "Using plain integer as NULL pointer" Sparse warning

Change 0 to NULL when initializing the test field of perf_msr structs to
avoid the following sparse warnings:

  make C=2 arch/x86/events/rapl.o

  CHECK   arch/x86/events/rapl.c
  ...
  arch/x86/events/rapl.c:540:59: warning: Using plain integer as NULL pointer
  arch/x86/events/rapl.c:542:59: warning: Using plain integer as NULL pointer
  arch/x86/events/rapl.c:543:59: warning: Using plain integer as NULL pointer
  arch/x86/events/rapl.c:544:59: warning: Using plain integer as NULL pointer
Signed-off-by: David Reaver <me@davidreaver.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230801155651.108076-1-me@davidreaver.com

arch/x86/events/rapl.c

@@ -533,11 +533,11 @@ static struct perf_msr intel_rapl_spr_msrs[] = {
  * - want to use same event codes across both architectures
  */
 static struct perf_msr amd_rapl_msrs[] = {
-	[PERF_RAPL_PP0]  = { 0, &rapl_events_cores_group, 0, false, 0 },
+	[PERF_RAPL_PP0]  = { 0, &rapl_events_cores_group, NULL, false, 0 },
 	[PERF_RAPL_PKG]  = { MSR_AMD_PKG_ENERGY_STATUS,  &rapl_events_pkg_group,   test_msr, false, RAPL_MSR_MASK },
-	[PERF_RAPL_RAM]  = { 0, &rapl_events_ram_group,   0, false, 0 },
-	[PERF_RAPL_PP1]  = { 0, &rapl_events_gpu_group,   0, false, 0 },
-	[PERF_RAPL_PSYS] = { 0, &rapl_events_psys_group,  0, false, 0 },
+	[PERF_RAPL_RAM]  = { 0, &rapl_events_ram_group,   NULL, false, 0 },
+	[PERF_RAPL_PP1]  = { 0, &rapl_events_gpu_group,   NULL, false, 0 },
+	[PERF_RAPL_PSYS] = { 0, &rapl_events_psys_group,  NULL, false, 0 },
 };
 
 static int rapl_cpu_offline(unsigned int cpu)