iommu: Fix compilation without CONFIG_IOMMU_INTEL

When the kernel is comiled with CONFIG_IRQ_REMAP=y but without
CONFIG_IOMMU_INTEL compilation fails since commit def054b0 with an
undefined reference to device_rbtree_find(). This patch makes sure that
intel specific code is only compiled with CONFIG_IOMMU_INTEL=y.

Signed-off-by: Bert Karwatzki <spasswolf@web.de>
Fixes: 80a9b50c ("iommu/vt-d: Improve ITE fault handling if target  device isn't present")
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20240307194419.15801-1-spasswolf@web.de


Signed-off-by: Joerg Roedel <jroedel@suse.de>