drm/amd/display: Fix uninitialized variables in dcn401

This fixes an UNINIT issue reported by Coverity.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c

@@ -805,7 +805,7 @@ enum dc_status dcn401_enable_stream_timing(
 	unsigned int event_triggers = 0;
 	int opp_cnt = 1;
 	int opp_inst[MAX_PIPES] = {0};
-	struct pipe_ctx *opp_heads[MAX_PIPES];
+	struct pipe_ctx *opp_heads[MAX_PIPES] = {0};
 	bool manual_mode;
 	unsigned int tmds_div = PIXEL_RATE_DIV_NA;
 	unsigned int unused_div = PIXEL_RATE_DIV_NA;