drm/amd/display: don't clean-up bottom pipe plane_state

In the scenario of setting underlay, dc_validate_global_state()
is called after constructing the context with all
relevant bottom_pipe related configurations in dm_update_planes_state().

Currently, in dc_validate_global_state(), without checking for bottom_pipe's
existence, the pipe_ctx structure is initialised to 0, hence
nullyfying the plane_state of bottom_pipe which shall be accessed
in populate_initial_data() called from bw_calcs().

Due to this null pointer access kernel panics and leads to reboot
when underlay is tried to set.

This patch fixes the issue by no longer clearing the top_pipe. This
workaround is no longer required.
Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

@@ -1729,14 +1729,6 @@ bool dc_validate_global_state(
 			dc, new_ctx) != DC_OK)
 		return false;
 
-	/* TODO without this SWDEV-114774 brakes */
-	for (i = 0; i < dc->res_pool->pipe_count; i++) {
-		struct pipe_ctx *pipe_ctx = &new_ctx->res_ctx.pipe_ctx[i];
-
-		if (pipe_ctx->top_pipe)
-			memset(pipe_ctx, 0, sizeof(*pipe_ctx));
-	}
-
 	for (i = 0; new_ctx && i < new_ctx->stream_count; i++) {
 		struct dc_stream_state *stream = new_ctx->streams[i];