UBI: use __packed instead of __attribute__((packed))

There was an attempt to standartize various "__attribute__" and
other macros in order to have potentially portable and more
consistent code, see commit 82ddcb040570411fc2d421d96b3e69711c670328.

Note, that commit refers Rober Love's blog post, but the URL
is broken, the valid URL is:
http://blog.rlove.org/2005/10/with-little-help-from-your-compiler.html

Moreover, nowadays checkpatch.pl warns about using
__attribute__((packed)):

"WARNING: __packed is preferred over __attribute__((packed))"

It is not a big deal for UBI to use __packed, so let's do it.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h
index 503ea9b..6fb8ec2 100644
--- a/drivers/mtd/ubi/ubi-media.h
+++ b/drivers/mtd/ubi/ubi-media.h
@@ -164,7 +164,7 @@
 	__be32  image_seq;
 	__u8    padding2[32];
 	__be32  hdr_crc;
-} __attribute__ ((packed));
+} __packed;
 
 /**
  * struct ubi_vid_hdr - on-flash UBI volume identifier header.
@@ -292,7 +292,7 @@
 	__be64  sqnum;
 	__u8    padding3[12];
 	__be32  hdr_crc;
-} __attribute__ ((packed));
+} __packed;
 
 /* Internal UBI volumes count */
 #define UBI_INT_VOL_COUNT 1
@@ -373,6 +373,6 @@
 	__u8    flags;
 	__u8    padding[23];
 	__be32  crc;
-} __attribute__ ((packed));
+} __packed;
 
 #endif /* !__UBI_MEDIA_H__ */