KVM: arm: replace WARN_ON with pr_warn for UNKNOWN type

euleros inclusion
category: bugfix
bugzilla: 46842
CVE: NA

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In addition to the Kunpeng processor, other CPU processors
may be supported. The call trace here may cause confusion.

Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Xiangyou Xie <xiexiangyou@huawei.com>
Reviewed-by: Ying Fang <fangying1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>