Fix m32r __xchg

the #endif  /* CONFIG_SMP */ should cover the default condition, or it may cause
bad parameter to be silently missed.

To make it work correctly, we have to remove the ifdef CONFIG SMP surrounding
__xchg_called_with_bad_pointer declaration. Thanks to Adrian Bunk for detecting
this.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Hirokazu Takata <takata@linux-m32r.org>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>