devfreq: Update the callback function for governor_bw_vbif

Update the callback function used by governor_bw_vbif to get the current
bandwidth settings from the GPU to include the IB, AB and an opaque
data pointer.

Change-Id: Ic0dedbad4ea9f0d85d99841d7f15c7be5eb63b8f
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>