classes/sanity: remove broken TARGET_ARCH check

classes/sanity: remove broken TARGET_ARCH check

The variable name has been typo'd as TARGE_ARCH since it was introduced
some time ago, so the check has never worked. Fixing the typo shows that
the test is not quite functional, so let's just remove it:

http://lists.linuxtogo.org/pipermail/openembedded-core/2011-October/010613.html

(From OE-Core rev: 897a9b1dddef385253b16ea7c193483e0ea679b6)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>