drm/amdgpu: fix ptr check warning in gfx9 ip_dump

Change if (ptr == NULL) to if (!ptr) for a better
format and fix the warning.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

@@ -2129,7 +2129,7 @@ static void gfx_v9_0_alloc_ip_dump(struct amdgpu_device *adev)
 	uint32_t inst;
 
 	ptr = kcalloc(reg_count, sizeof(uint32_t), GFP_KERNEL);
-	if (ptr == NULL) {
+	if (!ptr) {
 		DRM_ERROR("Failed to allocate memory for GFX IP Dump\n");
 		adev->gfx.ip_dump_core = NULL;
 	} else {
@@ -2142,7 +2142,7 @@ static void gfx_v9_0_alloc_ip_dump(struct amdgpu_device *adev)
 		adev->gfx.mec.num_queue_per_pipe;
 
 	ptr = kcalloc(reg_count * inst, sizeof(uint32_t), GFP_KERNEL);
-	if (ptr == NULL) {
+	if (!ptr) {
 		DRM_ERROR("Failed to allocate memory for Compute Queues IP Dump\n");
 		adev->gfx.ip_dump_compute_queues = NULL;
 	} else {