cpu-minor: fix store-release issuing

cpu-minor: fix store-release issuing

Store with release flag are treated like store conditionals and are not
bufferable. Also they are only sent when the store buffer is empty to
satisfy the release semantics.

Change-Id: I253ec5ecd39901b14d0dc8efbc82cf7e4b07f08f
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27135
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>