Revert "get the raw value when BackendConcrete is used for an eval"
Revert "get the raw value when BackendConcrete is used for an eval"

This reverts commit 4b3cfb2e144de4485e64f6b0172eb64f11890603 because it
breaks fidget.

angr/claripy,chubbymaggie/claripy,avain/claripy