habanalabs: remove set but not used variable 'ctx'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/misc/habanalabs/device.c: In function hpriv_release:
drivers/misc/habanalabs/device.c:45:17: warning: variable ctx set but not used [-Wunused-but-set-variable]

It is never used since commit eb7caf84 ("habanalabs:
maintain a list of file private data objects")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

drivers/misc/habanalabs/device.c

@@ -42,12 +42,10 @@ static void hpriv_release(struct kref *ref)
 {
 	struct hl_fpriv *hpriv;
 	struct hl_device *hdev;
-	struct hl_ctx *ctx;
 
 	hpriv = container_of(ref, struct hl_fpriv, refcount);
 
 	hdev = hpriv->hdev;
-	ctx = hpriv->ctx;
 
 	put_pid(hpriv->taskpid);