KVM: PPC: Book3S HV: Fix ppc_breakpoint_available compile error

arch/powerpc/kvm/book3s_hv.c: In function ‘kvmppc_h_set_mode’:
arch/powerpc/kvm/book3s_hv.c:745:8: error: implicit declaration of function ‘ppc_breakpoint_available’
   if (!ppc_breakpoint_available())
        ^~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 398e712c ("KVM: PPC: Book3S HV: Return error from h_set_mode(SET_DAWR) on POWER9")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>