Raise exception if invalid IP is specified

This patch ensures that all values specified for the configuration
option netapp_controller_ips are valid, rather than logging and
continuing with only the valid addresses.

Closes-Bug: 1396718

Change-Id: I180dc74e4535bfde19f1741cff975f5ec675dd21
(cherry picked from commit 3748994b58e4255958365b0939056cca8c323c9a)