xsk: Fix typo in xsk_umem_consume_tx and xsk_generic_xmit comments

s/backpreassure/backpressure/
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20200421232927.21082-1-tklauser@distanz.ch

net/xdp/xsk.c

@@ -322,7 +322,7 @@ bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc)
 		if (!xskq_cons_peek_desc(xs->tx, desc, umem))
 			continue;
 
-		/* This is the backpreassure mechanism for the Tx path.
+		/* This is the backpressure mechanism for the Tx path.
 		 * Reserve space in the completion queue and only proceed
 		 * if there is space in it. This avoids having to implement
 		 * any buffering in the Tx path.
@@ -406,7 +406,7 @@ static int xsk_generic_xmit(struct sock *sk)
 		addr = desc.addr;
 		buffer = xdp_umem_get_data(xs->umem, addr);
 		err = skb_store_bits(skb, 0, buffer, len);
-		/* This is the backpreassure mechanism for the Tx path.
+		/* This is the backpressure mechanism for the Tx path.
 		 * Reserve space in the completion queue and only proceed
 		 * if there is space in it. This avoids having to implement
 		 * any buffering in the Tx path.