make all pm block own their display data

That allows to keep track of the different selections from the different
windows.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/powerdebug.c b/powerdebug.c
index 1873b1b..3a2edac 100644
--- a/powerdebug.c
+++ b/powerdebug.c
@@ -177,12 +177,12 @@
 	if (options->selectedwindow == CLOCK) {
 
 		if (keystroke == KEY_DOWN) {
-			display_next_line();
+			display_next_line(CLOCK);
 			*cont = true;
 		}
 
 		if (keystroke == KEY_UP) {
-			display_prev_line();
+			display_prev_line(CLOCK);
 			*cont = true;
 		}