image-fit: make local function static

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/common/image-fit.c b/common/image-fit.c
index 2016d1e..a272ea2 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -1434,7 +1434,7 @@
 		printf("%s  FDT:          %s\n", p, uname);
 }
 
-int fit_image_select(const void *fit, int rd_noffset, int verify)
+static int fit_image_select(const void *fit, int rd_noffset, int verify)
 {
 	fit_image_print(fit, rd_noffset, "   ");