KVM: remove the unused parameter of gfn_to_pfn_memslot

The parameter, 'kvm', is not used in gfn_to_pfn_memslot, we can happily remove
it

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f85cc21..4f77f7a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2518,7 +2518,7 @@
 
 	hva = gfn_to_hva_memslot(slot, gfn);
 
-	return hva_to_pfn_atomic(vcpu->kvm, hva);
+	return hva_to_pfn_atomic(hva);
 }
 
 static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu,