ARM64: Relax 4K MMU mapping alignment

[carlocaione]

The problem came up in #45737

In same (rare) cases you want to map a MMIO region that is either smaller or not aligned to 4K. This is currently not supported by the MMU driver.

We have two solutions here:

1. We map the physical 4k-aligned address to different virtual addresses.
2. We check whether the mapping overlaps with an existing mapping and fix / extend the mapping when required.

[github-actions]

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[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.