power: reset: Add force warm reboot support

Some entities, such as PCIe on the LE platforms, 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: Id47ac11fcfa35f36b0fbb53e9a0d9cedad437a17
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>