msm: kgsl: Bring in the GPU frequency governor

Add a copy of the Adreno GPU frequency governor as of
01dafb76 ("Merge "power: qpnp-qnovo5: Add standalone class param"").

Instead of keeping the governor in drivers/devfreq, move it to the GPU
driver directory so that it can share a header file with the GPU driver.

Change-Id: Ic0dedbada21ca0310ce1ce69126fa0096c70c2e6
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>