debug/pe: delete unnecessary type conversions
debug/pe: delete unnecessary type conversions

Fixes issue 7104.

LGTM=iant
R=golang-dev, iant
CC=golang-codereviews
https://codereview.appspot.com/61480049

Committer: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang