drm/amd/display: Minor cleanup for DCN401 cursor related code

Move pipe_ctx variables to start of the function and add a helpful comment
Co-authored-by: Sridevi Arvindekar <sarvinde@amd.com>
Reviewed-by: Ilya Bakoulin <ilya.bakoulin@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Sridevi Arvindekar <sarvinde@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/dcn20/dcn20_hwseq.c

@@ -2800,6 +2800,11 @@ void dcn20_reset_back_end_for_pipe(
 	if (i == dc->res_pool->pipe_count)
 		return;
 
+/*
+ * In case of a dangling plane, setting this to NULL unconditionally
+ * causes failures during reset hw ctx where, if stream is NULL,
+ * it is expected that the pipe_ctx pointers to pipes and plane are NULL.
+ */
 	pipe_ctx->stream = NULL;
 	DC_LOG_DEBUG("Reset back end for pipe %d, tg:%d\n",
 					pipe_ctx->pipe_idx, pipe_ctx->stream_res.tg->inst);

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

@@ -1099,6 +1099,8 @@ void dcn401_set_cursor_position(struct pipe_ctx *pipe_ctx)
 	int prev_odm_offset = 0;
 	int next_odm_width = 0;
 	int next_odm_offset = 0;
+	struct pipe_ctx *next_odm_pipe = NULL;
+	struct pipe_ctx *prev_odm_pipe = NULL;
 
 	int x_pos = pos_cpy.x;
 	int y_pos = pos_cpy.y;
@@ -1110,6 +1112,7 @@ void dcn401_set_cursor_position(struct pipe_ctx *pipe_ctx)
 		}
 	}
 
+
 	/**
 	 * DCN4 moved cursor composition after Scaler, so in HW it is in
 	 * recout space and for HW Cursor position programming need to
@@ -1157,8 +1160,8 @@ void dcn401_set_cursor_position(struct pipe_ctx *pipe_ctx)
 	 * next/prev_odm_offset is to account for scaled modes that have underscan
 	 */
 	if (odm_combine_on) {
-		struct pipe_ctx *next_odm_pipe = pipe_ctx->next_odm_pipe;
-		struct pipe_ctx *prev_odm_pipe = pipe_ctx->prev_odm_pipe;
+		next_odm_pipe = pipe_ctx->next_odm_pipe;
+		prev_odm_pipe = pipe_ctx->prev_odm_pipe;
 
 		while (next_odm_pipe != NULL) {
 			next_odm_width += next_odm_pipe->plane_res.scl_data.recout.width;