FROMLIST: iommu/iova: Add support for IOVA max alignment tuning

IOVAs are aligned to the smallest PAGE_SIZE order, where the requested
IOVA can fit. But this might not work for all use-cases. It can cause
IOVA fragmentation in some multimedia and 8K video use-cases that may
require larger buffers to be allocated and mapped.

When the above allocation pattern is used with the current alignment
scheme, the IOVA space could be quickly exhausted for 32bit devices.

In order to get better IOVA space utilization and reduce fragmentation,
a new kernel command line parameter is introduced to make the alignment
limit configurable by the user during boot.

Bug: 190519428
Change-Id: I0c8e72370fc3266a5a242837d82aae4f9831aef3
Link: https://lore.kernel.org/r/1634148667-409263-1-git-send-email-quic_c_gdjako@quicinc.com/


Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>