ARM: dts: msm: use VDD_CX, VDD_MX, VDD_MMCX regulator phandles on SDMSHRIKE

Switch the regulator supply phandles used for VDD_CX, VDD_MX, and
VDD_MMCX so that device tree configurations are clearer.

Change-Id: I198b272dda19285ad6b6fd9af43b0711639002e2
Signed-off-by: David Collins <collinsd@codeaurora.org>