sparc64: Build failure due to commit f1600e549b94 (sparc: Make sparc64 use scalable lib/iommu-common.c functions)

[David Miller]

From: Guenter Roeck <linux at roeck-us.net>
Date: Sun, 19 Apr 2015 22:17:21 -0700

> The debug option is intended for all _other_ architectures, to
> ensure that changes made for those don't break alpha/s390
> builds. alpha/s390 have ARCH_NEEDS_WEAK_PER_CPU and don't need the
> debug option.

Ironically this would not create a build failure for the architectures
where this matters, because only powerpc has the like named percpu
symbol.

So it's not really meeting the stated objective in this case.