vdpa: Make use of PFN_PHYS/PFN_UP/PFN_DOWN helper macro

mainline inclusion
from mainline-v5.15-rc1
commit 729ce5a5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=729ce5a5bd6fda5eb2322a39db2287f1f26f92f3



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it's a nice refactor to make use of
PFN_PHYS/PFN_UP/PFN_DOWN helper macro

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20210802013717.851-1-caihuoqing@baidu.com


Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Pengyuan Zhao <zhaopengyuan@hisilicon.com>