thunderbolt: Use generic tb_nvm_[read|write]_data() for Thunderbolt 2/3 devices

Now that we have generic functionality available in nvm.c make the DMA
port code call it instead of duplicating the functionality.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Change-Id: I5c62161c2efbf8a0b31d0220d98815b2eee6f6c9