KVM: fix "Should it be static?" warnings from sparse

arch/x86/kvm/x86.c:495:5: sparse: symbol 'kvm_read_nested_guest_page' was not declared. Should it be static?
arch/x86/kvm/x86.c:646:5: sparse: symbol '__kvm_set_xcr' was not declared. Should it be static?
arch/x86/kvm/x86.c:1183:15: sparse: symbol 'max_tsc_khz' was not declared. Should it be static?
arch/x86/kvm/x86.c:1237:6: sparse: symbol 'kvm_track_tsc_matching' was not declared. Should it be static?
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -496,7 +496,7 @@ int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest_page_mmu);
 
-int kvm_read_nested_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+static int kvm_read_nested_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
 			       void *data, int offset, int len, u32 access)
 {
 	return kvm_read_guest_page_mmu(vcpu, vcpu->arch.walk_mmu, gfn,
@@ -647,7 +647,7 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
 	}
 }
 
-int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
+static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
 	u64 xcr0 = xcr;
 	u64 old_xcr0 = vcpu->arch.xcr0;
@@ -1193,7 +1193,7 @@ static atomic_t kvm_guest_has_master_clock = ATOMIC_INIT(0);
 #endif
 
 static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);
-unsigned long max_tsc_khz;
+static unsigned long max_tsc_khz;
 
 static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
 {
@@ -1247,7 +1247,7 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
 	return tsc;
 }
 
-void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
+static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
 {
 #ifdef CONFIG_X86_64
 	bool vcpus_matched;