ARM: dts: qcom: add VDD_MX and CX subnodes for MMCX dependencies on lito

Add VDD_MX and VDD_CX rpmh-regulator subnodes which are used by
the VDD_MMCX regulator device.  Configure these sub nodes so that
a request for VDD_CX >= minimum operating level is present any
time that VDD_MMCX is enabled.

Change-Id: I4dfa08018ca05c0b167c42611779258c077240bd
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>