1. use error code defined in errno.h instead of 1.
2. panic if error occured while adding devices to VM0 domain.
3. panic if failed to reqeust irq for iommu.
The two panic added would only occurs before any VM starts running.
Tracked-On: #1855
Signed-off-by: Binbin Wu <binbin.wu@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>