ARM: dts: msm: Add GDSC devices for MSM ZIRC

MSM Zirc has two GDSC devices. Add them in DT to allow
the client driver to control them.

Change-Id: I9f5b93100c7ec749d19a793d1e3a41c551d9be93
Signed-off-by: Tianyi Gou <tgou@codeaurora.org>