power-supply: Use 'break' instead of 'continue' to end loop

In few routines, we need to end the do-while loop when no more "power-supplies"
are available. Currently we are doing 'continue' which will make the
'while(np)' conditional statement run again.

Skip this by doing a 'break' instead.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>