lisa.target: Add info log when disabling/enabling idle states
lisa.target: Add info log when disabling/enabling idle states

Also move disabling idle states inside the try/except statement, so that
re-enabling happens if an exception is raised while disabling.

ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,credp/lisa,ARM-software/lisa