x86/mce: Reuse one of the u16 padding fields in 'struct mce'

... to save the error severity of the MCE and whether the
reported address of the error is usable.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1439396985-12812-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/uapi/asm/mce.h

@@ -15,7 +15,8 @@ struct mce {
 	__u64 time;	/* wall time_t when error was detected */
 	__u8  cpuvendor;	/* cpu vendor as encoded in system.h */
 	__u8  inject_flags;	/* software inject flags */
-	__u16  pad;
+	__u8  severity;
+	__u8  usable_addr;
 	__u32 cpuid;	/* CPUID 1 EAX */
 	__u8  cs;		/* code segment */
 	__u8  bank;	/* machine check bank */