Reapply "Enable CFI for riscv64"

This reverts commit 49dcf795.

The previous init crash was caused by the kernel defaulting to Sv57 and
the CFI shadow implementation in bionic assuming a 48-bit virtual
address space. With 5-level paging disabled in cuttlefish, we can again
enable CFI.

Bug: 293884796
Link: https://github.com/google/android-riscv64/issues/45
Test: cuttlefish boots
Change-Id: Ibcc02cf7ca6e396fd58674c648abf9f84daa260e