tools/testing/cxl: Require cache invalidation bypass

The typical environment where cxl_test is run, QEMU, does not support
cpu_cache_invalidate_memregion(). Add the 'test' bypass symbols to the
configuration check.

Reported-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/167026948179.3527561.4535373655515827457.stgit@dwillia2-xfh.jf.intel.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>