xtensa: iss/network: provide release() callback

stable inclusion
from stable-v5.10.137
commit fb4c1555f93f11fd6188c62fdd2c0d22e09a3ff5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb4c1555f93f11fd6188c62fdd2c0d22e09a3ff5



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[ Upstream commit 8864fb83 ]

Provide release() callback for the platform device embedded into struct
iss_net_private and registered in the iss_net_configure so that
platform_device_unregister could be called for it.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>