Remove debug command 'vuart' which is used to change VM's console's base
and irq before bringing up with uefi.
But after vuart's resuffle, the gloable variables vuart_com_irq and
vuart_com_base is not used anymore, vuart gets the base and irq from
its configuration. So the command can not work.
Tracked-On: #2987
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>