thunderbolt: Use 64-bit DMA mask if supported by the platform

PCI defaults to 32-bit DMA mask but this device is capable of full
64-bit addressing, so make sure we first try 64-bit DMA mask before
falling back to the default 32-bit.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>