tnapi is being initialized and then immediately updated and
hence the initialiation is redundant.  Clean up the warning
by moving the declaration and initialization to the inside
of the for-loop.

Cleans up clang scan-build warning:
warning: Value stored to 'tnapi' during its initialization is never read
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>