Fix golint warnings in testutils/call.go
Fix golint warnings in testutils/call.go

benfleis/tchannel,benfleis/tchannel,vanloswang/tchannel,chenwenbin928/tchannel,vanloswang/tchannel,savaki/tchannel,Zirpon/tchannel,hustxiaoc/tchannel,Zirpon/tchannel,chenwenbin928/tchannel,vanloswang/tchannel,savaki/tchannel,benfleis/tchannel,i/tchannel,savaki/tchannel,RyanTech/tchannel,hustxiaoc/tchannel,sasa233/tchannel,bunnyblue/tchannel,i/tchannel,Zirpon/tchannel,i/tchannel,chenwenbin928/tchannel,sasa233/tchannel,RyanTech/tchannel,sasa233/tchannel,RyanTech/tchannel,hustxiaoc/tchannel,bunnyblue/tchannel,bunnyblue/tchannel