revert "msm: 8064: Add regulator supply for DDR3 memory"

This reverts commit 994ff121.
PM8921 MPP7 no longer must be kept high at all times for targets
using PCDDR3 memory because newer hardware ensures that memory is
always powered when necessary.

Change-Id: I4919abceb875b9ea22e6b2c0bd617280deb7e65b
Signed-off-by: David Collins <collinsd@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>