[RFE] Support for timeout in UCS's Power.set_power_state

[Ruby Loo]

(in ironic/drivers/modules/ucs/power.py)

Power.set_power_state() does not support the optional timeout parameter.

The timeout parameter was introduced with [1], in Bare Metal version 1.27, and it is

:param timeout: timeout (in seconds) positive integer (> 0) for any
                power state. ``None`` indicates to use default timeout.

[1] http://specs.openstack.org/openstack/ironic-specs/specs/approved/enhance-power-interface-for-soft-reboot-and-nmi.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/521425

[Ruby Loo (rloo)]

Similar to the other rfes for drivers that don't support timeout (e.g. https://bugs.launchpad.net/ironic/+bug/1732283), I am approving this RFE as it falls under driver feature parity category.