cxl/region: Fix out-of-bounds access in cxl_cancel_auto_attach()

In the Linux kernel, the following vulnerability has been resolved: cxl/region: Fix out-of-bounds access in cxl_cancel_auto_attach() In cxl_cancel_auto_attach(), it assumes cxled->pos is a valid index for accessing p->targets[]. However, cxled->pos can be set to negative errno in cxl_region_sort_targets() if cxl_calc_interleave_pos() fails. This causes the driver to use a negative index to access p->targets[], resulting in out-of-bounds access. Fix it by walking p->targets[] instead of using cxled->pos directly.