Documentation/driver-api/cxl: remove page-allocator quirk section

Documentation/driver-api/cxl: remove page-allocator quirk section

The node/zone quirk section of the cxl documentation is incorrect.
The actual reason for fallback allocation misbehavior in the
described configuration is due to a kswapd/reclaim thrashing scenario
fixed by the linked patch.  Remove this section.

Link: https://lore.kernel.org/linux-mm/20250919162134.1098208-1-hannes@cmpxchg.org/
Signed-off-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>