bootm: mark local boot_os[] table static

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

common/cmd_bootm.c

@@ -129,7 +129,7 @@ int do_bootelf (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
 static boot_os_fn do_bootm_integrity;
 #endif
 
-boot_os_fn * boot_os[] = {
+static boot_os_fn *boot_os[] = {
 #ifdef CONFIG_BOOTM_LINUX
 	[IH_OS_LINUX] = do_bootm_linux,
 #endif