arm: blue: set correct number of ion heaps

* Commit 8bf8af13e5 "kernel_sony_msm8x60: some voltages fix."
  bumped the number to 8 (why?)
* Set it back to 7, which is the number of heaps that we have

Change-Id: Ibfd61a3352b0f33aa4b589696d641f4d832ccb3b