iommu/io-pgtable-dart: Add 4-level page table support

iommu/io-pgtable-dart: Add 4-level page table support

DARTs on t602x SoCs are of the t8110 variant but have an IAS of 42,
which means optional support for an extra page table level.

Refactor the PTE management to support an arbitrary level count, and
then calculate how many levels we need for any given configuration.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Sven Peter <sven@kernel.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Link: https://lore.kernel.org/r/20250821-apple-dart-4levels-v2-2-e39af79daa37@jannau.net
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>