numactl: skip test case when target platform doesn't have 2 CPU node

when current test platform doesn't have 2 or more CPU node, the test
case would report FAIL, according to numa test script and numademo
code, when return code=77 should be skip test, so using SKIP instead
of FAIL in test script.

Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>