thunderbolt: Update Kconfig to allow building on other architectures.

Thunderbolt 3 and USB4 shouldn't be x86 only.

Tested on a SolidRun HoneyComb (ARM Cortex-A72) with a
Gigabyte Titan Ridge Thunderbolt 3 PCIe card (JHL7540).

Signed-off-by: David Manouchehri <david.manouchehri@riseup.net>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>