Make highlighted_row variable static

Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
diff --git a/powerdebug.c b/powerdebug.c
index 0b26678..7eb9c5e 100644
--- a/powerdebug.c
+++ b/powerdebug.c
@@ -18,7 +18,7 @@
 #include "regulator.h"
 #include "powerdebug.h"
 
-int highlighted_row;
+static int highlighted_row;
 
 void usage(void)
 {