arm/dt: msm8226/8610: Remove the vdd_mss-supply property

The vdd_mss-supply property is not required on the MSM8610
and MSM8226. This is because the modem is on the CX power
rail in these targets and is perfectly capable of voting
for CX on its own.

Change-Id: Ia2fe50b76856a3f27969fe2dcb31331defc5c563
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>