eth: fbnic: fix stampinn typo in a comment

Fix a typo:
 stampinn -> stamping

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20250624142834.3275164-3-kuba@kernel.org


Signed-off-by: Paolo Abeni <pabeni@redhat.com>