uname -m was leaving a newline in $arch, and not passing the tests.

Also, printing the unknown arch on failure is probably helpful.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>