ARM: dts: msm: Optimize uart console sleep config

The uart console sleep configuration can be optimized for
power saving by reducing the drive strength and changing
its bias to pull-down. Presently the change is applicable
to msm8916, msm8994, msm8939 and msmzirc only.

Change-Id: I3fa8e6e66e3335a5d0569f0fa3010023d58bf548
Signed-off-by: Kaushal Kumar <kaushalk@codeaurora.org>