kvm tools: Fix powerpc build after kvm__dump_mem() change

Commit 21692d1 (Beautify debug output) broke the powerpc build because
it changed the signature for kvm__dump_mem() but didn't update all callers.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Pekka Enberg <penberg@kernel.org>