mlx5: avoid build warnings on 32-bit

The mlx5 driver passes a string pointer in through a 'u64' variable,
which on 32-bit machines causes a build warning:

drivers/net/ethernet/mellanox/mlx5/core/debugfs.c: In function 'qp_read_field':
drivers/net/ethernet/mellanox/mlx5/core/debugfs.c:303:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

The code is in fact safe, so we can shut up the warning by adding
extra type casts.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/debugfs.c

@@ -300,11 +300,11 @@ static u64 qp_read_field(struct mlx5_core_dev *dev, struct mlx5_core_qp *qp,
 		param = qp->pid;
 		break;
 	case QP_STATE:
-		param = (u64)mlx5_qp_state_str(be32_to_cpu(ctx->flags) >> 28);
+		param = (unsigned long)mlx5_qp_state_str(be32_to_cpu(ctx->flags) >> 28);
 		*is_str = 1;
 		break;
 	case QP_XPORT:
-		param = (u64)mlx5_qp_type_str((be32_to_cpu(ctx->flags) >> 16) & 0xff);
+		param = (unsigned long)mlx5_qp_type_str((be32_to_cpu(ctx->flags) >> 16) & 0xff);
 		*is_str = 1;
 		break;
 	case QP_MTU:
@@ -464,7 +464,7 @@ static ssize_t dbg_read(struct file *filp, char __user *buf, size_t count,
 
 
 	if (is_str)
-		ret = snprintf(tbuf, sizeof(tbuf), "%s\n", (const char *)field);
+		ret = snprintf(tbuf, sizeof(tbuf), "%s\n", (const char *)(unsigned long)field);
 	else
 		ret = snprintf(tbuf, sizeof(tbuf), "0x%llx\n", field);