net/mlx4: make the array states static const, makes object smaller

Don't populate the array states on the stack but instead it
static const. Makes the object code smaller by 79 bytes.

Before:
   text   data   bss    dec    hex filename
  21309   8304   192  29805   746d drivers/net/ethernet/mellanox/mlx4/qp.o

After:
   text   data   bss    dec    hex filename
  21166   8368   192  29726   741e drivers/net/ethernet/mellanox/mlx4/qp.o

(gcc version 10.2.0)
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NLeon Romanovsky <leonro@nvidia.com>
Reviewed-by: NTariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20210801153742.147304-1-colin.king@canonical.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx4/qp.c

@@ -917,7 +917,7 @@ int mlx4_qp_to_ready(struct mlx4_dev *dev, struct mlx4_mtt *mtt,
 {
 	int err;
 	int i;
-	enum mlx4_qp_state states[] = {
+	static const enum mlx4_qp_state states[] = {
 		MLX4_QP_STATE_RST,
 		MLX4_QP_STATE_INIT,
 		MLX4_QP_STATE_RTR,