ARM: dts: msm: Change VDD_MMCX's min. voltage to LOW_SVS for SDMSHRIKE

Change the minimum and initial voltage levels for the VDD_MMCX regulator
supply to LOW_SVS. This corresponds to the minimum operation level of
hardware blocks powered by VDD_MMCX.

CRs-Fixed: 2231304
Change-Id: I23a7ce0599f5d2928737266044b914cb122fa152
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>