cpu-o3: Fix handling of some mem. order violations

cpu-o3: Fix handling of some mem. order violations

This patch fixes the handling of memory order violations due to snoops
targeting out-of-order loads: the re-execution triggered in these cases
is achieved by raising a ReExec fault, but such a fault was not handled
correctly after the code changes introduced in changeset 46da8fb.

Change-Id: I2abe161a90468412f56cb28dcc92729326cba1cd
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21819
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Timothy Hayes <timothy.hayes@arm.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>