HV: instr_emul: Unify params passing to emulate_xxx

There are so many __unused prefix spaning the emulate_xxx functions. This patch
unify the parameters of emulate_xxx to avoid it.

  - All emulate_xxx functions are defined as emulate_xxx(struct vcpu *vcpu, instr_emul_vie *vie)
    or emulate_xxx(struct vcpu *vcpu, instr_emul_vie *vie, struct vm_guest_paging *paging).

  - Move mmio_read/write to instr_emul.c and call them directly.

Signed-off-by: Kaige Fu <kaige.fu@intel.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>

Author: KaigeFu