MIPS: KVM: Skip memory cleaning in kvm_mips_commpage_init()

The commpage is allocated using kzalloc(), so there's no need of cleaning
the memory of the kvm_mips_commpage struct and its internal mips_coproc.

Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>