msm: clock: change vdd_corner to 1D array

Previously a 2D array was used for vdd_corner.  Since the dimensions
are known, 1D array saves one level of pointers and works equally well.
It's also easier to dynamically construct a 1D array.

Change-Id: Ic873ca40b383ff12363becd74537f58fcd2fdbf7
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>