target/ppc: Avoid warning message for zero process table entries

A translation that encounters a process table entry that is zero is
something that Linux does to cause certain kernel NULL pointer
dereferences to fault. It is not itself a programming error, so avoid
the guest error log.

Message-ID: <20241219034035.1826173-5-npiggin@gmail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
1 file changed