iommu/vt-d: Fix checks and print in dmar_fault_dump_ptes()

iommu/vt-d: Fix checks and print in dmar_fault_dump_ptes()

There are some issues in dmar_fault_dump_ptes():

1. return value of phys_to_virt() is used for checking if an entry is
   present.
2. dump is confusing, e.g., "pasid table entry is not present", confusing
   by unpresent pasid table vs. unpresent pasid table entry. Current code
   means the former.
3. pgtable_walk() is called without checking if page table is present.

Fix 1 by checking present bit of an entry before dump a lower level entry.
Fix 2 by removing "entry" string, e.g., "pasid table is not present".
Fix 3 by checking page table present before walk.

Take issue 3 for example, before fix:

[  442.240357] DMAR: pasid dir entry: 0x000000012c83e001
[  442.246661] DMAR: pasid table entry[0]: 0x0000000000000000
[  442.253429] DMAR: pasid table entry[1]: 0x0000000000000000
[  442.260203] DMAR: pasid table entry[2]: 0x0000000000000000
[  442.266969] DMAR: pasid table entry[3]: 0x0000000000000000
[  442.273733] DMAR: pasid table entry[4]: 0x0000000000000000
[  442.280479] DMAR: pasid table entry[5]: 0x0000000000000000
[  442.287234] DMAR: pasid table entry[6]: 0x0000000000000000
[  442.293989] DMAR: pasid table entry[7]: 0x0000000000000000
[  442.300742] DMAR: PTE not present at level 2

After fix:
...
[  357.241214] DMAR: pasid table entry[6]: 0x0000000000000000
[  357.248022] DMAR: pasid table entry[7]: 0x0000000000000000
[  357.254824] DMAR: scalable mode page table is not present

Fixes: 914ff7719e8a ("iommu/vt-d: Dump DMAR translation structure when DMA fault occurs")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/r/20241024092146.715063-2-zhenzhong.duan@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>