drop the old fetch behavior for pre Cargo 0.13.0

This behavior is flakey and doesn't work from Cargo 0.13.0 and newer
which aren't part of this repo anymore.

classes/cargo.bbclass

@@ -83,10 +83,6 @@ oe_cargo_fix_env () {
 EXTRA_OECARGO_PATHS ??= ""
 
 cargo_do_compile () {
-	# prevent cargo from trying to fetch down new data
-	mkdir -p "${WORKDIR}/cargo_home/registry/index/github.com-1ecc6299db9ec823"
-	touch "${WORKDIR}/cargo_home/registry/index/github.com-1ecc6299db9ec823/.cargo-index-lock"
-
 	oe_cargo_fix_env
 	oe_cargo_build
 }