net/nbd: fix PKG_CPE_ID

net/nbd: fix PKG_CPE_ID

There is not a single CVE linked to network_block_device:nbd so use
network_block_device_project:network_block_device instead:
https://nvd.nist.gov/products/cpe/search/results?keyword=cpe:2.3:a:network_block_device_project:network_block_device

Fixes: 299e5b0a9bce19d6e96cb9ff217028b36ee2dd36 (treewide: add PKG_CPE_ID for better cvescanner coverage)
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
(cherry picked from commit 222df5ed5d469f42034fea230666c011e7ea3e30)