drm/amdgpu: Fix ras debugfs data parse

Unzero char is accepted by sscanf, so when data is structure but
unexpectedly return error invalid;
Signed-off-by: xinhui pan <xinhui.pan@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -241,7 +241,7 @@ static int amdgpu_ras_debugfs_ctrl_parse_data(struct file *f,
 		op = 1;
 	else if (sscanf(str, "inject %32s %8s", block_name, err) == 2)
 		op = 2;
-	else if (sscanf(str, "%32s", block_name) == 1)
+	else if (str[0] && str[1] && str[2] && str[3])
 		/* ascii string, but commands are not matched. */
 		return -EINVAL;