KVM: RISC-V: Convert to the gfn-based MMU notifier callbacks

Intel inclusion
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I7S3VQ


CVE: NA

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Align with upstreaming risc-v code, to use the gfn-base MMU notifier
APIs, which do the hva->gfn lookup in common code.

Note: RISC-V's MMU notifier support was in introduced in upstreaming
commit 9955371c ("RISC-V: KVM: Implement MMU notifiers"), which
uses the gfn-based MMU notififer in the first place. And with commit
b4c5936c ("KVM: Kill off the old hva-based MMU notifier callbacks")
backported, we can feel safe to use the latest, upstreaming aligned
implementation now.

Also, KVM_ARCH_WANT_NEW_MMU_NOTIFIER_APIS was used, so that other
archs which can not easily use the gfn-based MMU notifiers can continue
to use their hva-based code.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>