Fail power setup if node is not connected

Fail power setup if node is not connected

Currently, if getting info from a node fails, power setup just
continues with the next node. This is wrong since power levels
have to be adjusted for each node in the path sequentially.

Instead, return false from setPower if getting node info fails.
Also adapt UT.

JIRA: TRNSPRTPCE-715
Change-Id: I44fdfbe871b320b2d9e2bc174c769d6a521fb50c
Signed-off-by: Jonas Mårtensson <jonas.martensson@smartoptics.com>
Co-authored-by: Gilles Thouenon <gilles.thouenon@orange.com>