s390/qdio: split qdio_inspect_queue()

The callers know what type of queue they want to inspect. Introduce
type-specific variants to inspect an {Input,Output} queue, so that we
can avoid one function parameter and some conditional branches in the
hot paths.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>