ion: msm: Rename msm_ion_of.[c/h] to msm_ion.[c/h]

Rename msm_ion_of.[c/h] to msm_ion.[c/h], as the OF portion is
a bit of a misnomer, considering that the file supports
more than just the OF parsing machinery.

Change-Id: I013cbdb78cb031ab7521f55873ed9fb031cbbed5
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>