KVM: x86/mmu: Use kvm_x86_call() instead of manual static_call()

KVM: x86/mmu: Use kvm_x86_call() instead of manual static_call()

Use KVM's preferred kvm_x86_call() wrapper to invoke static calls related
to mirror page tables.

No functional change intended.

Fixes: 77ac7079e66d ("KVM: x86/tdp_mmu: Propagate building mirror page tables")
Fixes: 94faba8999b9 ("KVM: x86/tdp_mmu: Propagate tearing down mirror page tables")
Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20250331182703.725214-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>