RAS/AMD/ATL: Add debug prints for DF register reads

The ATL will fail early if the DF register access fails due to missing
PCI IDs in the amd_nb code. There aren't any clear indicators on why the
ATL will fail to load in this case.

Add a couple of debug print statements to highlight reasons for failure.

A common scenario is missing support for new hardware. If the ATL fails
to load on a system, and there is interest to support it, then dynamic
debugging can be enabled to help find the cause for failure. If there is
no interest in supporting ATL on a new system, then these failures will
be silent.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20241021152158.2525669-1-yazen.ghannam@amd.com