drm/amd/display: Adjust code identation and other minor details

This commit replaces spaces with tabs in multiple functions and adjusts
the indentation in some other parts of the code to improve readability.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>