hv:Move several inline APIs from vm.h to *.c

-- move vm_pic() from vm.h to vpic.c since it is
   only used in vpic.c
-- move vm_ioapic() from vm.h to vioapic.c
   change vioapic_reset(struct acrn_vioapic *vioapic) -->
          vioapic_reset(struct acrn_vm *vm)
   then vm_vioapic() is only used in vioapic.c
-- move vm_vuart() from vm.h to vuart.c,
   now this api is used in vuart.c and shell.c

Tracked-On: #1842
Signed-off-by: Mingqiang Chi <mingqiang.chi@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Reviewed-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/debug/vuart.c

@@ -122,6 +122,11 @@ static uint8_t vuart_intr_reason(const struct acrn_vuart *vu)
 	}
 }
 
+struct acrn_vuart *vm_vuart(struct acrn_vm *vm)
+{
+	return &(vm->vuart);
+}
+
 /*
  * Toggle the COM port's intr pin depending on whether or not we have an
  * interrupt condition to report to the processor.