backlight: lp855x: Ensure regulators are disabled on probe failure

If probing the LP885x backlight fails after the regulators have been
enabled, then the following warning is seen when releasing the
regulators ...

WARNING: CPU: 1 PID: 289 at drivers/regulator/core.c:2051 _regulator_put.part.28+0x158/0x160
Modules linked in: tegra_xudc lp855x_bl(+) host1x pwm_tegra ip_tables x_tables ipv6 nf_defrag_ipv6
CPU: 1 PID: 289 Comm: systemd-udevd Not tainted 5.6.0-rc2-next-20200224 #1
Hardware name: NVIDIA Jetson TX1 Developer Kit (DT)

...

Call trace:
_regulator_put.part.28+0x158/0x160
regulator_put+0x34/0x50
devm_regulator_release+0x10/0x18
release_nodes+0x12c/0x230
devres_release_all+0x34/0x50
really_probe+0x1c0/0x370
driver_probe_device+0x58/0x100
device_driver_attach+0x6c/0x78
__driver_attach+0xb0/0xf0
bus_for_each_dev+0x68/0xc8
driver_attach+0x20/0x28
bus_add_driver+0x160/0x1f0
driver_register+0x60/0x110
i2c_register_driver+0x40/0x80
lp855x_driver_init+0x20/0x1000 [lp855x_bl]
do_one_initcall+0x58/0x1a0
do_init_module+0x54/0x1d0
load_module+0x1d80/0x21c8
__do_sys_finit_module+0xe8/0x100
__arm64_sys_finit_module+0x18/0x20
el0_svc_common.constprop.3+0xb0/0x168
do_el0_svc+0x20/0x98
el0_sync_handler+0xf4/0x1b0
el0_sync+0x140/0x180

Fix this by ensuring that the regulators are disabled, if enabled, on
probe failure.

Finally, ensure that the vddio regulator is disabled in the driver
remove handler.

Signed-off-by: Jon Hunter <[e-mail]>
Reviewed-by: Daniel Thompson <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/video/backlight/lp855x_bl.c

···
 		ret = regulator_enable(lp->enable);
 		if (ret < 0) {
 			dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
-			return ret;
+			goto disable_supply;
 		}
 
 		/*
···
 	ret = lp855x_configure(lp);
 	if (ret) {
 		dev_err(lp->dev, "device config err: %d", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	ret = lp855x_backlight_register(lp);
 	if (ret) {
 		dev_err(lp->dev,
 			"failed to register backlight. err: %d\n", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 	if (ret) {
 		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	backlight_update_status(lp->bl);
+
 	return 0;
+
+disable_vddio:
+	if (lp->enable)
+		regulator_disable(lp->enable);
+disable_supply:
+	if (lp->supply)
+		regulator_disable(lp->supply);
+
+	return ret;
 }
 
 static int lp855x_remove(struct i2c_client *cl)
···
 
 	lp->bl->props.brightness = 0;
 	backlight_update_status(lp->bl);
+	if (lp->enable)
+		regulator_disable(lp->enable);
 	if (lp->supply)
 		regulator_disable(lp->supply);
 	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);