x86/kvm: Fix compilation warning in non-x86_64 builds

On non-x86_64 builds, helpers gtod_is_based_on_tsc() and
kvm_guest_supported_xfd() are defined but never used.  Because these are
static inline but are in a .c file, some compilers do warn for them with
-Wunused-function, which becomes an error if -Werror is present.

Add #ifdef so they are only defined in x86_64 builds.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220218034100.115702-1-leobras@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -989,10 +989,12 @@ static inline u64 kvm_guest_supported_xcr0(struct kvm_vcpu *vcpu)
 	return vcpu->arch.guest_fpu.fpstate->user_xfeatures;
 }
 
+#ifdef CONFIG_X86_64
 static inline u64 kvm_guest_supported_xfd(struct kvm_vcpu *vcpu)
 {
 	return kvm_guest_supported_xcr0(vcpu) & XFEATURE_MASK_USER_DYNAMIC;
 }
+#endif
 
 static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
@@ -2361,10 +2363,12 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
 	return tsc;
 }
 
+#ifdef CONFIG_X86_64
 static inline int gtod_is_based_on_tsc(int mode)
 {
 	return mode == VDSO_CLOCKMODE_TSC || mode == VDSO_CLOCKMODE_HVCLOCK;
 }
+#endif
 
 static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
 {