ARM: dts: qcom: apq8064-cm-qs600: Use stdout-path

Use stdout-path so that we don't have to put the console on the
kernel command line.

Cc: Mike Rapoport <mike.rapoport@gmail.com>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>