gpu: nvgpu: remove interface names and static classes to create dev nodes

Remove static class definition and registration for iGPU and dGPU.
Create the class dynamically in gk20a_user_init() and setup the callback
function to create devnode name based on GPU type.

For now add nvgpu_pci_devnode() callback for dGPU that sets correct
dev node path for dGPUs. For iGPU, Android apparently does not honor dev
node path set in callback and hence override the device name for iGPU
with function nvgpu_devnode().

Destroy the class in gk20a_user_deinit().

This will overall be helpful in adding multiple classes and dev nodes
for each GPU instance in MIG mode.

Set GPU device pointer as the parent of new devices created with
device_create(). This is helpful in getting GPU device name in
callback function nvgpu_pci_devnode().

Update functions to not pass class structure and interface names :
nvgpu_probe()
gk20a_user_init()
gk20a_user_deinit()
nvgpu_remove()

Remove static interface name format like INTERFACE_NAME since it is no
longer needed.

Update GK20A_NUM_CDEVS to 10 since there are 10 dev nodes per GPU right
now.

Jira NVGPU-5648

Change-Id: I5d41db5a0f87fa4a558297fb4135a9fbfcd51080
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2423492
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/os/linux/driver_common.h

@@ -18,12 +18,9 @@
 #define NVGPU_LINUX_DRIVER_COMMON
 
 struct gk20a;
-struct class;
 
 int nvgpu_probe(struct gk20a *g,
-		const char *debugfs_symlink,
-		const char *interface_name,
-		struct class *device_class);
+		const char *debugfs_symlink);
 
 void nvgpu_init_gk20a(struct gk20a *g);