cxl/hdm: Add more HDM decoder debug messages at startup

cxl/hdm: Add more HDM decoder debug messages at startup

A recent debug session yielded a couple debug messages that were useful
for determining the reason why the driver was or was not falling back
to CXL range register emulation, and for identifying decoder setting
enumeration problems.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/168149845668.792294.11814353796371419167.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>