net: hns3: fix return of random stack value

Currently, a random stack value is being returned because variable
_ret_ is not properly initialized. This variable is actually not
used anymore and it should be removed.

Fix this by removing all instances of variable ret and return 0.

Fixes: 64749c9c ("net: hns3: remove redundant return value of hns3_uninit_all_ring()")
Addresses-Coverity-ID: 1501700 ("Uninitialized scalar variable")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>