cpu-o3: Fix too strict assert condition in writeback()

cpu-o3: Fix too strict assert condition in writeback()

The assert() in the LSQ writeback() only allowed ReExec faults.
However, a SplitRequest which completed the translation in
PartialFault state (i.e. any but the very first cacheline
translation failed) may end up here. The assert() condition is
extended accordingly.

The patch also removes the superfluous/unused Complete/Squashed
states from the LSQ request. (The completion of the request is
recorded in the flags still.)

Change-Id: Ie575f4d3b4d5295585828ad8c7d3f4c7c1fe15d0
Signed-off-by: Gabor Dozsa <gabor.dozsa@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19174
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>