make imgfill_cmdline static

src/hci/commands/image_cmd.c

  * @v nargs		Argument count
  * @v args		Argument list
  */
-void imgfill_cmdline ( struct image *image, unsigned int nargs, char **args ) {
+static void imgfill_cmdline ( struct image *image, unsigned int nargs, 
+                              char **args ) {
 	size_t used = 0;
 
 	image->cmdline[0] = '\0';