x86: Fix the dom0 booting hang when VT-d is enabled.

x86: Fix the dom0 booting hang when VT-d is enabled.

Dom0 C/S 593 hooks the pci bus probe and remove function. When
probing a function at booting time, it will first add the device into
Dom0's list through a hypercall, then execute the driver's probe
function. If the probe function fails, another hypercall is called to
remove the device from Dom0's list. But for some RMRR devices, for
example, USB devices, they may still be in use for some operation by
BIOS at booting time. So when removing those kind of devices, we
should still keep the RMRR information.

Also add a small fix for "for_each_rmrr_device".

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>