x86/mce: Fix copy/paste error in exception table entries

Back in commit:

  92b0729c34cab ("x86/mm, x86/mce: Add memcpy_mcsafe()")

... I made a copy/paste error setting up the exception table entries
and ended up with two for label .L_cache_w3 and none for .L_cache_w2.

This means that if we take a machine check on:

  .L_cache_w2: movq 2*8(%rsi), %r10

then we don't have an exception table entry for this instruction
and we can't recover.

Fix: s/3/2/

Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 92b0729c34cab ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Link: http://lkml.kernel.org/r/1490046030-25862-1-git-send-email-tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/lib/memcpy_64.S

@@ -290,7 +290,7 @@ EXPORT_SYMBOL_GPL(memcpy_mcsafe_unrolled)
 	_ASM_EXTABLE_FAULT(.L_copy_leading_bytes, .L_memcpy_mcsafe_fail)
 	_ASM_EXTABLE_FAULT(.L_cache_w0, .L_memcpy_mcsafe_fail)
 	_ASM_EXTABLE_FAULT(.L_cache_w1, .L_memcpy_mcsafe_fail)
-	_ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
+	_ASM_EXTABLE_FAULT(.L_cache_w2, .L_memcpy_mcsafe_fail)
 	_ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
 	_ASM_EXTABLE_FAULT(.L_cache_w4, .L_memcpy_mcsafe_fail)
 	_ASM_EXTABLE_FAULT(.L_cache_w5, .L_memcpy_mcsafe_fail)