Rename __attribute__((packed)) --> __packed

Also unify __attribute__ ((..)) to __attribute__((..)) and
handle ((__packed__)) like ((packed))

Change-Id: Ie60a51c3fa92b5009724a5b7c2932e361bf3490c
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/15921
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

payloads/libpayload/liblz4/lz4_wrapper.c

@@ -98,7 +98,7 @@ struct lz4_frame_header {
 	};
 	/* + uint64_t content_size iff has_content_size is set */
 	/* + uint8_t header_checksum */
-} __attribute__((packed));
+} __packed;
 
 struct lz4_block_header {
 	union {
@@ -110,7 +110,7 @@ struct lz4_block_header {
 	};
 	/* + size bytes of data */
 	/* + uint32_t block_checksum iff has_block_checksum is set */
-} __attribute__((packed));
+} __packed;
 
 size_t ulz4fn(const void *src, size_t srcn, void *dst, size_t dstn)
 {