ulib: Add a way to obtain the version

It is possible to simply read the 'version_string' variable, but it
seems better to add a proper API call to get this. It is already
defined in lib/ulib/ulib.c

Add a prototype to u-boot-lib.h

Make use of it from the demo program.

Fix the comment for ulib_uninit() while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>

examples/ulib/demo.c

@@ -31,7 +31,7 @@ int main(int argc, char *argv[])
 	}
 
 	demo_show_banner();
-	printf("U-Boot version: %s\n", version_string);
+	printf("U-Boot version: %s\n", ulib_get_version());
 	printf("\n");
 
 	/* Use U-Boot's os_open to open a file */

include/u-boot-lib.h

@@ -25,10 +25,17 @@ struct global_data;
 int ulib_init(char *progname);
 
 /**
- * ulib_uninit() shut down the U-Boot librrary
+ * ulib_uninit() - shut down the U-Boot library
  *
  * Call this when your program has finished using the library, before it exits
  */
 void ulib_uninit(void);
 
+/**
+ * ulib_get_version() - Get the version string
+ *
+ * Return: Full U-Boot version string
+ */
+const char *ulib_get_version(void);
+
 #endif