UBI: set correct gluebi device size

In case of static volumes, make emulated MTD device size to
be equivalent to data size, rather then volume size.

Reported-by: John Smith <john@arrows.demon.co.uk>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/ubi.h

@@ -374,9 +374,11 @@ void ubi_calculate_reserved(struct ubi_device *ubi);
 #ifdef CONFIG_MTD_UBI_GLUEBI
 int ubi_create_gluebi(struct ubi_device *ubi, struct ubi_volume *vol);
 int ubi_destroy_gluebi(struct ubi_volume *vol);
+void ubi_gluebi_updated(struct ubi_volume *vol);
 #else
 #define ubi_create_gluebi(ubi, vol) 0
 #define ubi_destroy_gluebi(vol) 0
+#define ubi_gluebi_updated(vol)
 #endif
 
 /* eba.c */