liquidio: clear the correct memory

There is a cut and paste bug here so we accidentally clear the first
few bytes of "resp" a second time instead clearing "ctx".

Fixes: 50c0add5 ("liquidio: refactor interrupt moderation code")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>