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/coreinfo/cbfs_module.c

@@ -44,7 +44,7 @@ struct cbheader {
 	u32 offset;
 	u32 architecture;
 	u32 pad[1];
-} __attribute__ ((packed));
+} __packed;
 
 struct cbfile {
 	u64 magic;
@@ -53,7 +53,7 @@ struct cbfile {
 	u32 checksum;
 	u32 offset;
 	char filename[0];
-} __attribute__ ((packed));
+} __packed;
 
 static int filecount = 0, selected = 0, start_row = 0;
 static char **filenames;