iommu/io-pgtable-dart: Only set subpage protection disable for DART 1

iommu/io-pgtable-dart: Only set subpage protection disable for DART 1

Subpage protection can't be disabled on t6000-style darts,
as such the disable flag no longer applies, and probably
even affects something else.

Fixes: dc09fe1c5edd ("iommu/io-pgtable-dart: Add DART PTE support for t6000")
Signed-off-by: Asahi Lina <lina@asahilina.net>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20250219-dart2-no-sp-disable-v1-1-9f324cfa4e70@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>