drm/amd/display: Clean up for DCN1 clock debug logging

[Why]
To prepare for clock debug logging. With the exception of removing
max_supported_dppclk_khz from logs, there are no functional changes.

[How]
Add clk_bypass struct and clean up buffer logic

Signed-off-by: Fatemeh Darbehani <fatemeh.darbehani@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Su Chung <Su.Chung@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>