x86: fix up bootparam.h for userspace inclusion

commit 8b664aa6 (x86, boot: add linked
list of struct setup_data) put a new struct in bootparam.h, but didn't
use the userspace-safe types.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Huang Ying <ying.huang@intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/asm-x86/bootparam.h

@@ -14,10 +14,10 @@
 
 /* extensible setup data list node */
 struct setup_data {
-	u64 next;
-	u32 type;
-	u32 len;
-	u8 data[0];
+	__u64 next;
+	__u32 type;
+	__u32 len;
+	__u8 data[0];
 };
 
 struct setup_header {