ARM: dts: msm: Remove support for gdsc_mmss on MSMCOBALT

The MMSS GDSC should only be disabled during the XO
shutdown path on MSMCOBALT. There is no need to
explicitly support it in linux since it should be
left enabled by RPM.

Change-Id: I0e2cdf1e6026553a53f176dc10810b10b596e67e
CRs-Fixed: 988307
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>