drm/amd/display: Add profiling tools for bandwidth validation

[Why]
We used this change to investigate the performance of bandwidth validation,
it will be useful to have if we need to investigate further.

[How]
We use performance counter tick numbers to profile performance, they live
at dc->debug.bw_val_profile (set .enable in debugger to turn on measuring).

Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha &lt;Bhawanpreet <Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>