Changes:

    Simplify nested complexity
    If an if blocks ends with a return statement then remove the else nesting.

Most of the changes has also been reported in golint https://goreportcard.com/report/github.com/ethereum/go-ethereum#golint
# Conflicts:
#	cmd/utils/flags.go
#	console/bridge.go
#	crypto/bls12381/g2.go
#	les/benchmark.go
#	les/lespay/server/balance.go
#	les/lespay/server/balance_tracker.go
#	les/lespay/server/prioritypool.go
#	les/odr_requests.go
#	les/serverpool.go
#	les/serverpool_test.go
#	p2p/nodestate/nodestate_test.go
#	trie/committer.go