power: reset: Add force warm reboot support

Some entities, such as PCIe on the LE pltforms, do not want
to lose the communication link on a system reboot. As a result,
add support to force warm reboot of the system and preserve the
link.

Change-Id: Ib0c3435f92393eae31afee9c144d2aaf2abcb512
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>