This reverts commit e100a73b.

This reverts commit 176183df.

The redirect may be speculative and the branch instruction may be replayed.
pnpc should be set to the updated pnpc, the same as the newly-fetched instructions.

The goal of this commit is to remove 'implict val p: XSConfig' in our code becasue it's inconvenient

Exceptions should have higher priority over branch misprediction redirects.