drm/amd/display: Drop needless check for link->link_id.id

drm/amd/display: Drop needless check for link->link_id.id

[WHY]
The switch/case in `link_detect_sink_signal_type` already detects the
link ID of `CONNECTOR_ID_HDMI_TYPE_A`.

[How]
Drop the extra match.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>