net/mlx5e: Tx, Strict the room needed for SQ edge NOPs

We use NOPs to populate the WQ fragment edge if the WQE does not fit
in frag, to avoid WQEs crossing a page boundary (or wrap-around the WQ).

The upper bound on the needed number of NOPs is one WQEBB less than
the largest possible WQE, for otherwise the WQE would certainly fit.
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h

@@ -6,7 +6,7 @@
 
 #include "en.h"
 
-#define MLX5E_SQ_NOPS_ROOM  MLX5_SEND_WQE_MAX_WQEBBS
+#define MLX5E_SQ_NOPS_ROOM (MLX5_SEND_WQE_MAX_WQEBBS - 1)
 #define MLX5E_SQ_STOP_ROOM (MLX5_SEND_WQE_MAX_WQEBBS +\
 			    MLX5E_SQ_NOPS_ROOM)