i2c: nvidia-gpu: make pm_ops static

sparse rightfully says:

warning: symbol 'gpu_i2c_driver_pm' was not declared. Should it be static?
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-nvidia-gpu.c

@@ -349,7 +349,7 @@ static int gpu_i2c_resume(struct device *dev)
 	return 0;
 }
 
-UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, NULL, gpu_i2c_resume, NULL);
+static UNIVERSAL_DEV_PM_OPS(gpu_i2c_driver_pm, NULL, gpu_i2c_resume, NULL);
 
 static struct pci_driver gpu_i2c_driver = {
 	.name		= "nvidia-gpu",