pnv/xive2: Quiet down some error messages

pnv/xive2: Quiet down some error messages

When dumping the END and NVP tables ("info pic" from the HMP) on the
P10 model, we're likely to be flooded with error messages such as:

  XIVE[0] - VST: invalid NVPT entry f33800 !?

The error is printed when finding an empty VSD in an indirect
table (thus END and NVP tables with skiboot), which is going to happen
when dumping the xive state. So let's tune down those messages. They
can be re-enabled easily with a macro if needed.

Those errors were already hidden on xive/P9, for the same reason.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20230531150537.369350-1-fbarrat@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>