[Backport] KVM: 反合一些遗漏的fix补丁

[yechao-w]

• Linux-6.12
  47d40d9 RISC-V: KVM: Don't zero-out PMU snapshot area before freeing data

• Linux-6.13
  ea6398a RISC-V: KVM: Fix csr_write -> csr_set for HVIEN PMU overflow bit

• Linux-6.14
  d252435 riscv: KVM: Remove unnecessary vcpu kick
  351e02b riscv: KVM: Fix SBI sleep_type use

• Linux-6.15
  2d117e6 RISC-V: KVM: Teardown riscv specific bits after kvm_exit