gpu: nvgpu: add channel event id support

With NVGPU_IOCTL_CHANNEL_EVENTS_CTRL, nvgpu can
raise events to User space. But user space
cannot distinguish between various types of events.
To overcome this, we need finer-grained API to
deliver various events to user space.

Remove old API NVGPU_IOCTL_CHANNEL_EVENTS_CTRL,
and all the support for this API (we can remove
this since User space has not started using this
API at all)

Add new API NVGPU_IOCTL_CHANNEL_EVENT_ID_CTRL
which will accept an event_id (like BPT.INT or
BPT.PAUSE), a command to enable the event,
and return a file descriptor on which
we can raise the event (if cmd=enable)
Event is disabled when file descriptor is closed

Add file operations "gk20a_event_id_ops"
to support polling on event fd

Also add API gk20a_channel_get_event_data_from_id()
to get event_data of event from its id

Bug 200089620

Change-Id: I5288f19f38ff49448c46338c33b2a927c9e02254
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1030775
(cherry picked from commit 5721ce2735950440bedc2b86f851db08ed593275)
Reviewed-on: http://git-master/r/1120318
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

drivers/gpu/nvgpu/gk20a/gk20a.c

@@ -108,7 +108,6 @@ static const struct file_operations gk20a_channel_ops = {
 	.compat_ioctl = gk20a_channel_ioctl,
 #endif
 	.unlocked_ioctl = gk20a_channel_ioctl,
-	.poll = gk20a_channel_poll,
 };
 
 static const struct file_operations gk20a_ctrl_ops = {