kvm: x86: Remove redundant mp_state initialization

kvm_arch_reset_vcpu initializes mp_state, and that function is invoked
right after kvm_arch_init_vcpu.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
