selftest/net/forwarding: declare NETIFS p9 p10

stable inclusion
from stable-v5.10.88
commit cac0fd4b9bd385b96b6548dcda7e22e03d2694b2
bugzilla: 186058 https://gitee.com/openeuler/kernel/issues/I4QW6A

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cac0fd4b9bd385b96b6548dcda7e22e03d2694b2



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[ Upstream commit 71da1aec ]

The recent GRE selftests defined NUM_NETIFS=10. If the users copy
forwarding.config.sample to forwarding.config directly, they will get
error "Command line is not complete" when run the GRE tests, because
create_netif_veth() failed with no interface name defined.

Fix it by extending the NETIFS with p9 and p10.

Fixes: 2800f248 ("selftests: forwarding: Test multipath hashing on inner IP pkts for GRE tunnel")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>