drm/amdgpu: Add description for AMD_IP_BLOCK_TYPE_VPE

AMD_IP_BLOCK_TYPE_VPE is a new IP BLOCK type for Video Processing Engine,
but currently lacks description.

Fix the documentation warning:
warning: Enum value 'AMD_IP_BLOCK_TYPE_VPE' not described in
enum 'amd_ip_block_type'
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Reviewed-by: Lang Yu <lang.yu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/include/amd_shared.h

@@ -83,6 +83,7 @@ enum amd_apu_flags {
 * @AMD_IP_BLOCK_TYPE_VCN: Video Core/Codec Next
 * @AMD_IP_BLOCK_TYPE_MES: Micro-Engine Scheduler
 * @AMD_IP_BLOCK_TYPE_JPEG: JPEG Engine
+* @AMD_IP_BLOCK_TYPE_VPE: Video Processing Engine
 * @AMD_IP_BLOCK_TYPE_UMSCH_MM: User Mode Schduler for Multimedia
 * @AMD_IP_BLOCK_TYPE_NUM: Total number of IP block types
 */