thunderbolt: Add support for ASMedia NVM image format

Add support for ASMedia specific NVM image format. This makes it
possible to upgrade the NVM firmware of ASMedia routers in addition to
Intel ones.

Signed-off-by: Szuying Chen <Chloe_Chen@asmedia.com.tw>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>