net: neigh: remove redundant assignment to variable bucket

The variable bucket is being initialized with a value that is never
read and it is being updated later with a new value in a following
for-loop. The initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>