hack/build: Update release-pin location to defaultReleaseImageOriginal

Catching up with a31e12f (release: Allow release image to be
directly substituted into binary, 2019-03-15, #1422).

Author: wking

hack/build.sh

@@ -45,7 +45,7 @@ release)
 	TAGS="${TAGS} release"
 	if test -n "${RELEASE_IMAGE}"
 	then
-		LDFLAGS="${LDFLAGS} -X github.com/openshift/installer/pkg/asset/ignition/bootstrap.defaultReleaseImage=${RELEASE_IMAGE}"
+		LDFLAGS="${LDFLAGS} -X github.com/openshift/installer/pkg/asset/ignition/bootstrap.defaultReleaseImageOriginal=${RELEASE_IMAGE}"
 	fi
 	if test -n "${RHCOS_BUILD_NAME}"
 	then