Revert "Handle "hardware" bootconfig parameter as "androidboot.hardware""

This reverts commit 0a799bdf.
Now that the kernel bootconfig feature has been to updated to handle
mixed subkeys and values, androidboot.hardware parameter is supported.

Test: build and boot Cuttlefish with "androidboot.hardware=cutf_vm"
Bug: 191502832
Merged-In: I0e436a27730d20689bc6974562c3e88d744385db
Change-Id: I0e436a27730d20689bc6974562c3e88d744385db