powerpc/numa: Drop dbg in favour of pr_debug

powerpc supported numa=debug which is not documented. This option was
used to print early debug output. However something more flexible can be
achieved by using CONFIG_DYNAMIC_DEBUG.

Hence drop dbg (and numa=debug) in favour of pr_debug

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
[mpe: Rebase on to powerpc/next form2 affinity changes]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210826100521.412639-2-srikar@linux.vnet.ibm.com