iommu: Fix htmldocs warnings in sysfs-kernel-iommu_groups

iommu: Fix htmldocs warnings in sysfs-kernel-iommu_groups

Below warnings are fixed:

Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Unexpected indentation.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Block quote ends without a blank line; unexpected unindent.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Enumerated list ends without a blank line; unexpected unindent.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Unexpected indentation.
Documentation/ABI/testing/sysfs-kernel-iommu_groups:38: WARNING: Block quote ends without a blank line; unexpected unindent.

Fixes: 63a816749d86 ("iommu: Document usage of "/sys/kernel/iommu_groups/<grp_id>/type" file")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/linux-next/20201126174851.200e0e58@canb.auug.org.au/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201126090603.1511589-1-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>