fix valid_index

Previous code would create issues for lane masks different from
ALL_ACTIVE_LANE_MASK, due to a pipelining bug. Although the currently officially
supported behavior is only either one lane active or all lanes active, this is a
very simple change that helps us prepare in case we want to support other lanes
in the future, and removes some extra logic (a comparison and a mux), which can
improve timing.

Signed-off-by: Laez Barbosa <[email protected]>

Author: LBFFilho

library/spi_engine/spi_engine_execution/spi_engine_execution_shiftreg_data_assemble.v

@@ -159,7 +159,7 @@ module spi_engine_execution_shiftreg_data_assemble #(
           lane_index <= 0;
         end
         lane_index_d <= lane_index;
-        valid_index <= (lane_mask == ALL_ACTIVE_LANE_MASK) ? lane_index : valid_indices[lane_index_d];
+        valid_index <= valid_indices[lane_index];
       end else if (sdo_toshiftreg) begin
         last_handshake_int <= 1'b0;
       end