gpio: qpnp-gpio: Add missing call to spmi_driver_unregister

Call the spmi unregistration routine as required when exiting the
module.

Change-Id: Id87148945626be89e94cd31c5cd946f9b8653bb3
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
diff --git a/drivers/gpio/qpnp-gpio.c b/drivers/gpio/qpnp-gpio.c
index e715adc..bc0904ec 100644
--- a/drivers/gpio/qpnp-gpio.c
+++ b/drivers/gpio/qpnp-gpio.c
@@ -1079,6 +1079,7 @@
 #ifdef CONFIG_GPIO_QPNP_DEBUG
 	debugfs_remove_recursive(driver_dfs_dir);
 #endif
+	spmi_driver_unregister(&qpnp_gpio_driver);
 }
 
 MODULE_DESCRIPTION("QPNP PMIC gpio driver");