devstack: Configure console device name
devstack: Configure console device name

Console device name is hardcoded to ttyS0 in ironic devstack plugin.
On some architecture, serial device name may not be ttyS0. For example,
ttyAMA0 for ARM.

This patch adds parameter IRONIC_TTY_DEV to configure console device
name, and keeps using ttyS0 if it's not set.

Closes-Bug: #1582564

Change-Id: I13c67e2c5d573c5b79776746e08a84c60861d6a7
Signed-off-by: Yibo Cai <e732a3f0de35687e82bda0008a72e443d2f69704@linaro.org>

SauloAislan/ironic,SauloAislan/ironic,pshchelo/ironic,devananda/ironic,openstack/ironic,NaohiroTamura/ironic,NaohiroTamura/ironic,bacaldwell/ironic,openstack/ironic,pshchelo/ironic,bacaldwell/ironic