thunderbolt: Add Kconfig option to disable PCIe tunneling

In typical cases PCIe tunneling is needed to make the devices fully
usable for the host system. However, it poses a security issue because
they can also use DMA to access the host memory. We already have two
ways of preventing this, one an IOMMU that is enabled on recent systems
by default and the second is the "authorized" attribute under each
connected device that needs to be written by userspace before a PCIe
tunnel is created. This option adds one more by adding a Kconfig option,
which is enabled by default, that can be used to make kernel binaries
where PCIe tunneling is completely disabled.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
References: https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_134314v1/bat-mtlp-9/boot0.txt
References: #11261


Signed-off-by: Imre Deak <imre.deak@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240604161618.1958674-1-imre.deak@intel.com


Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>