cxl/region: fix x9 interleave typo

CXL supports x3, x6 and x12 - not x9.

Fixes: 80d10a6c ("cxl/region: Add interleave geometry attributes")
Signed-off-by: Jim Harris <jim.harris@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Link: https://lore.kernel.org/r/169904271254.204936.8580772404462743630.stgit@ubuntu


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