RISC-V: KVM: Redirect AMO load/store misaligned traps to guest

The M-mode redirects an unhandled misaligned trap back
to S-mode when not delegating it to VS-mode(hedeleg).
However, KVM running in HS-mode terminates the VS-mode
software when back from M-mode.
The KVM should redirect the trap back to VS-mode, and
let VS-mode trap handler decide the next step.
Here is a way to handle misaligned traps in KVM,
not only directing them to VS-mode or terminate it.

Signed-off-by: wchen <waylingII@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>