drm/nouveau/secboot/gm20b: initialize pointer in gm20b_secboot_new()

We accidentally set "psb" which is a no-op instead of "*psb" so it
generates a static checker warning.  We should probably set it before
the first error return so that it's always initialized.

Fixes: 923f1bd2 ("drm/nouveau/secboot/gm20b: add secure boot support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/secboot/gm20b.c

@@ -129,6 +129,7 @@ gm20b_secboot_new(struct nvkm_device *device, int index,
 	struct gm200_secboot *gsb;
 	struct nvkm_acr *acr;
 
+	*psb = NULL;
 	acr = acr_r352_new(BIT(NVKM_SECBOOT_FALCON_FECS) |
 			   BIT(NVKM_SECBOOT_FALCON_PMU));
 	if (IS_ERR(acr))
@@ -137,10 +138,8 @@ gm20b_secboot_new(struct nvkm_device *device, int index,
 	acr->optional_falcons = BIT(NVKM_SECBOOT_FALCON_PMU);
 
 	gsb = kzalloc(sizeof(*gsb), GFP_KERNEL);
-	if (!gsb) {
-		psb = NULL;
+	if (!gsb)
 		return -ENOMEM;
-	}
 	*psb = &gsb->base;
 
 	ret = nvkm_secboot_ctor(&gm20b_secboot, acr, device, index, &gsb->base);