dm: power: Avoid case-insensitve match for child names

dm: power: Avoid case-insensitve match for child names

This is not user input (i.e. from the command line). It should be possible
to get the case correct and avoid the case-insensitive match. This will
help avoid sloppy device tree setups.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>