drm/amd/display: Add debug messages for dc_validate_boot_timing()

dc_validate_boot_timing() runs through an exhaustive list of checks to
determine whether a boot stream can be marked as seamless. When the
checks fail, a user will be left guessing what the reason was

Add debug statements that will be helpful to validate the specific
reason.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Link: https://lore.kernel.org/r/20250120194903.1048811-1-superm1@kernel.org


Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>