net: hinic: fix memory leak when reading function table

When the input parameter idx meets the expected case option in
hinic_dbg_get_func_table(), read_data is not released. Fix it.

Fixes: 5215e162 ("hinic: add support to query function table")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>