drm/amd/dc: Kill dc_conn_log_hex_linux()

DRM already supports tracing DPCD transactions, there's no reason for
the existence of this function. Also, it prints one byte per-line which
is way too loud. So, just remove it.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>