tools:iio:lsiio: add error handling
tools:iio:lsiio: add error handling

Add error handling to calls which can indicate a major problem by
returning an error code.
This also involves to change the type of dump_devices() from void to int.

Signed-off-by: Hartmut Knaack <4bccb8448924141fc676c25eb657b52ee47a361d@gmx.de>
Signed-off-by: Jonathan Cameron <09f65b71b7655725897b2fd41a09a0cefe2e1ace@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs