ECKD, FBA, and the DIAG discipline use slightly different block layer
settings. In preparation of even more diverse queue settings, make
dasd_setup_queue() a discipline function.
Signed-off-by: NJan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: NStefan Haberland <sth@linux.ibm.com>
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>