Revert "drm/[radeon|amdgpu]: Replace one-element array and use struct_size() helper"

This reverts commit 4541ea81.

This changes structs used by the hardware and breaks dpm on some cards.
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/si_dpm.c

@@ -5715,9 +5715,10 @@ static int si_upload_sw_state(struct amdgpu_device *adev,
 	int ret;
 	u32 address = si_pi->state_table_start +
 		offsetof(SISLANDS_SMC_STATETABLE, driverState);
+	u32 state_size = sizeof(SISLANDS_SMC_SWSTATE) +
+		((new_state->performance_level_count - 1) *
+		 sizeof(SISLANDS_SMC_HW_PERFORMANCE_LEVEL));
 	SISLANDS_SMC_SWSTATE *smc_state = &si_pi->smc_statetable.driverState;
-	size_t state_size = struct_size(smc_state, levels,
-					new_state->performance_level_count);
 
 	memset(smc_state, 0, state_size);
 

drivers/gpu/drm/amd/amdgpu/sislands_smc.h

@@ -186,7 +186,7 @@ struct SISLANDS_SMC_SWSTATE
     uint8_t                             levelCount;
     uint8_t                             padding2;
     uint8_t                             padding3;
-    SISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[];
+    SISLANDS_SMC_HW_PERFORMANCE_LEVEL   levels[1];
 };
 
 typedef struct SISLANDS_SMC_SWSTATE SISLANDS_SMC_SWSTATE;

drivers/gpu/drm/radeon/si_dpm.c

@@ -5253,9 +5253,10 @@ static int si_upload_sw_state(struct radeon_device *rdev,
 	int ret;
 	u32 address = si_pi->state_table_start +
 		offsetof(SISLANDS_SMC_STATETABLE, driverState);
+	u32 state_size = sizeof(SISLANDS_SMC_SWSTATE) +
+		((new_state->performance_level_count - 1) *
+		 sizeof(SISLANDS_SMC_HW_PERFORMANCE_LEVEL));
 	SISLANDS_SMC_SWSTATE *smc_state = &si_pi->smc_statetable.driverState;
-	size_t state_size = struct_size(smc_state, levels,
-					new_state->performance_level_count);
 
 	memset(smc_state, 0, state_size);