gpu: nvgpu: vgpu: add freq capping support

Currently callbacks from the PM_QOS framework (for
thermal events), result in a RPC call to set GPU frequency.

Since the governor will now be responsible for setting desired
rate, the max PM_QOS callback will now cap the possible
GPU frequency w/ a new RPC call to the server. The server
is responsible for setting the ultimate frequency
based on the cap & desired rates.

Jira VFND-3699

Change-Id: I806e309c40abc2f1381b6a23f2d898cfe26f9794
Signed-off-by: Sachit Kadle <skadle@nvidia.com>
Reviewed-on: http://git-master/r/1295543
(cherry picked from commit e81693c6e087f8f10a985be83715042fc590d6db)
Reviewed-on: http://git-master/r/1282467
(cherry picked from commit 7b4e0db647572e82a8d53e823c36b465781f4942)
Reviewed-on: http://git-master/r/1321836
(cherry picked from commit 57dafc08a5)
Reviewed-on: http://git-master/r/1313469
Tested-by: Aparna Das <aparnad@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Richard Zhao <rizhao@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

include/linux/tegra_vgpu.h

@@ -102,6 +102,7 @@ enum {
 	TEGRA_VGPU_CMD_CLEAR_SM_ERROR_STATE = 68,
 	TEGRA_VGPU_CMD_GET_GPU_CLK_RATE = 69,
 	TEGRA_VGPU_CMD_GET_GPU_FREQ_TABLE = 70,
+	TEGRA_VGPU_CMD_CAP_GPU_CLK_RATE = 71,
 	TEGRA_VGPU_CMD_PROF_MGT = 72,
 	TEGRA_VGPU_CMD_GET_TIMESTAMPS_ZIPPER = 74,
 };