cpu: Don't assert on branch target addresses

cpu: Don't assert on branch target addresses

We should assume a branch target can be any address.

JIRA: https://gem5.atlassian.net/browse/GEM5-483

Change-Id: I6f6da1f9260d6e8978536967dc7fcf1808965db2
Signed-off-by: Hsuan Hsu <hsuan.hsu@mediatek.com>
Signed-off-by: Howard Wang <Howard.Wang@mediatek.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28347
Reviewed-by: Trivikram Reddy <tvreddy@ucdavis.edu>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>