ARM: tegra: dvfs: Don't fail same level override request

ARM: tegra: dvfs: Don't fail same level override request

When new VDD_CORE override level is the same as the one already in
place do not return error from the override API.

Bug 1280293

Change-Id: Ic4393541308139c2ac9579acc8e2af47b144d521
Signed-off-by: Alex Frid <afrid@nvidia.com>
Reviewed-on: http://git-master/r/225378
(cherry picked from commit cea34a24e79f8be40fa5aaf6a38992a0d54e705e)
Reviewed-on: http://git-master/r/231750
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Matt Wagner <mwagner@nvidia.com>
Tested-by: Matt Wagner <mwagner@nvidia.com>