iommu/vt-d: Add debugfs support for Interrupt remapping

Debugfs extension for Intel IOMMU to dump Interrupt remapping table
entries for Interrupt remapping and Interrupt posting.

The file /sys/kernel/debug/iommu/intel/ir_translation_struct provides
detailed information, such as Index, Source Id, Destination Id, Vector
and the IRTE values for entries with the present bit set, in the format
shown.

Remapped Interrupt supported on IOMMU: dmar1
 IR table address:85e500000
 Entry SrcID   DstID    Vct IRTE_high           IRTE_low
 24    01:00.0 00000001 24  0000000000040100    000000010024000d
 25    01:00.0 00000004 22  0000000000040100    000000040022000d

Posted Interrupt supported on IOMMU: dmar5
 IR table address:85ec00000
 Entry SrcID   PDA_high PDA_low  Vct IRTE_high          IRTE_low
 4     43:00.0 0000000f ff765980 41  0000000f00044300   ff76598000418001
 5     43:00.0 0000000f ff765980 51  0000000f00044300   ff76598000518001

Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Co-Developed-by: Gayatri Kammela <gayatri.kammela@intel.com>
Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>