cxl: Fix unregister_region() callback parameter assignment

cxl: Fix unregister_region() callback parameter assignment

In devm_cxl_add_region(), devm_add_action_or_reset() is called by
passing in unregister_region() with data ptr of 'cxlr'. However, in
unregister_region(), the passed in parameter is incorrectly assumed to
be a 'struct device' rather than the 'cxlr' pointer. The code has been
working because 'struct device' is the first member of 'struct
cxl_region'. Issue found by inspection. Fix the assignment so that cxlr
is pointing directly to the passed in parameter.

Not flagged for -stable since there is no functional impact of this fix.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/170258123810.952211.3907381447996426480.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>