tools/iio/iio_utils:fix memory leak

[ Upstream commit f2edf0c819a4823cd6c288801ce737e8d4fcde06 ]

1. fopen sysfs without fclose.
2. asprintf filename without free.
3. if asprintf return error,do not need to free the buffer.

Signed-off-by: Yulong Zhang <yulong.zhang@metoak.net>
Link: https://lore.kernel.org/r/20230117025147.69890-1-yulong.zhang@metoak.net


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>