x86: kvm: mmu: make kvm_mmu_clear_all_pte_masks static

The kvm_mmu_clear_all_pte_masks interface is only used by kvm_mmu_module_init
locally, and does not need to be called by other module, make it static.

This patch cleans up sparse warning:
symbol 'kvm_mmu_clear_all_pte_masks' was not declared. Should it be static?
Signed-off-by: Gimcuan Hui <gimcuan@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -381,7 +381,7 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes);
 
-void kvm_mmu_clear_all_pte_masks(void)
+static void kvm_mmu_clear_all_pte_masks(void)
 {
 	shadow_user_mask = 0;
 	shadow_accessed_mask = 0;