None of the users actually look for the NULL value.  To avoid risk
of regression introducing a new value but forgetting to add a string
add a static assert to test AMD_PSTATE_MAX matches the array size.

Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
 drivers/cpufreq/amd-pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 0bc5013448873..a5b9e5baf4234 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -65,8 +65,8 @@ static const char * const amd_pstate_mode_string[] = {
 	[AMD_PSTATE_PASSIVE]     = "passive",
 	[AMD_PSTATE_ACTIVE]      = "active",
 	[AMD_PSTATE_GUIDED]      = "guided",
-	NULL,
 };
+static_assert(ARRAY_SIZE(amd_pstate_mode_string) == AMD_PSTATE_MAX);
 
 const char *amd_pstate_get_mode_string(enum amd_pstate_mode mode)
 {
-- 
2.43.0