trillian/ctfe: drop unused rpc deadline field
trillian/ctfe: drop unused rpc deadline field

RJPercival/certificate-transparency-go,RJPercival/certificate-transparency-go,google/certificate-transparency-go,daviddrysdale/certificate-transparency-go,google/certificate-transparency-go,daviddrysdale/certificate-transparency-go,daviddrysdale/certificate-transparency-go,google/certificate-transparency-go,RJPercival/certificate-transparency-go