update_flash: Use device tree to get firmware version details
update_flash: Use device tree to get firmware version details

On P9, OPAL exports firmware information via device tree
(/ibm,firmware-versions node). Even recent hostboot firmware on P8 BMC system
exports these information via mini device tree.

Lets add support to parse device tree to get firmware information. If firmware
information is not present in device tree then fall back to existing ipmi
method.

Signed-off-by: Vasant Hegde <a6d753843573f7bfed5075c1e875b0be8007a0ab@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <f4a317f2a73d762775eb462a22d913f1ae21c433@linux.vnet.ibm.com>

shenki/powerpc-utils,shenki/powerpc-utils,shenki/powerpc-utils