boards: siemens: iot2050: Re-enable bootstage reporting

This got lost while fixing up the condition in
board/siemens/iot2050/board.c

Fixes: b55881dd ("bootstage: Add SPL support")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Simon Glass <sjg@chromium.org>