powerpc/ptdump: Fix DEBUG_WX since generic ptdump conversion

In note_prot_wx() we bail out without reporting anything if
CONFIG_PPC_DEBUG_WX is disabled.

But CONFIG_PPC_DEBUG_WX was removed in the conversion to generic ptdump,
we now need to use CONFIG_DEBUG_WX instead.

Fixes: e0847283

 ("powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/20211203124112.2912562-1-mpe@ellerman.id.au