cxl/region: Add dev_dbg() detail on failure to allocate HPA space

cxl/region: Add dev_dbg() detail on failure to allocate HPA space

When the region driver fails while allocating HPA space for a
new region it can be because the parent resource, the CXL Window,
has no more available space.

In that case, the debug user sees this message:
cxl_core:alloc_hpa:555: cxl region2: failed to allocate HPA: -34

Expand the message like this:
cxl_core:alloc_hpa:555: cxl region8: HPA allocation error (-34) for size:0x20000000 in CXL Window 0 [mem 0xf010000000-0xf04fffffff flags 0x200]

Now the debug user can examine /proc/iomem and consider actions
like removing other allocations in that space or reducing the
size of their region request.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Link: https://lore.kernel.org/r/20231223004740.1401858-1-alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>