powerpc/lpar/debug: Initialize flags before printing debug message

With enabled DEBUG, there is a compile error:
"error: ‘flags’ is used uninitialized in this function".

This moves pr_devel() little further where @flags are initialized.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>