tree: Make internal functions static

None of these functions are used outside of the files they are defined
in, so make them all static.

Change-Id: Ie9cbe12d289bcedacf2f1bf483ae64ef8039ccc1
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/33667
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/print.c b/print.c
index 7eb5485..cfe6267 100644
--- a/print.c
+++ b/print.c
@@ -423,7 +423,7 @@
 }
 #endif
 
-void print_supported_devs(const struct programmer_entry prog, const char *const type)
+static void print_supported_devs(const struct programmer_entry prog, const char *const type)
 {
 	const struct dev_entry *const devs = prog.devs.dev;
 	msg_ginfo("\nSupported %s devices for the %s programmer:\n", type, prog.name);