drm/amd/display: fix a minor HDCP logging error

[why]
In HDCP Uninitialzed State, a CPIRQ event would cause log output
internal policy error because the CPIRQ event is not recognized as
unexpected event.

[how]
CPIRQ is issued in HDCP uninitialized state is unexpected.  We should
set unexpected event flag in event ctx.

Signed-off-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Ashley Thomas <Ashley.Thomas2@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>