v2: add table length check.

DC component expect PP to give max engine clock and
memory clock through pp_get_display_mode_validation_clocks
on DGPU as well.

This patch can fix MultiGPU-Display blank
out with 1 IGPU-4k display and 2 DGPU-two 4K
displays.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>