mshv: clean up SynIC state on kexec for L1VH

mshv: clean up SynIC state on kexec for L1VH

The reboot notifier that tears down the SynIC cpuhp state guards the
cleanup with hv_root_partition(), so on L1VH (where
hv_root_partition() is false) SINT0, SINT5, and SIRBP are never
cleaned up before kexec. The kexec'd kernel then inherits stale
unmasked SINTs and an enabled SIRBP pointing to freed memory.

Remove the hv_root_partition() guard so the cleanup runs for all
parent partitions.

Signed-off-by: Jork Loeser <jloeser@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>