mfd: rk808: Replace 'struct i2c_client' with 'struct device'

Put 'struct device' pointer into the MFD platform_data instead
of the 'struct i2c_client' pointer. This simplifies the code
and prepares the MFD for SPI support.

Tested-by: Diederik de Haas <didi.debian@cknow.org> # Rock64, Quartz64 Model A + B
Tested-by: Vincent Legoll <vincent.legoll@gmail.com> # Pine64 QuartzPro64
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230504173618.142075-5-sebastian.reichel@collabora.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/rk808.c

@@ -577,7 +577,7 @@ static int rk808_power_off(struct sys_off_data *data)
 	}
 	ret = regmap_update_bits(rk808->regmap, reg, bit, bit);
 	if (ret)
-		dev_err(&rk808->i2c->dev, "Failed to shutdown device!\n");
+		dev_err(rk808->dev, "Failed to shutdown device!\n");
 
 	return NOTIFY_DONE;
 }
@@ -600,7 +600,7 @@ static int rk808_restart(struct sys_off_data *data)
 	}
 	ret = regmap_update_bits(rk808->regmap, reg, bit, bit);
 	if (ret)
-		dev_err(&rk808->i2c->dev, "Failed to restart device!\n");
+		dev_err(rk808->dev, "Failed to restart device!\n");
 
 	return NOTIFY_DONE;
 }
@@ -720,7 +720,7 @@ static int rk808_probe(struct i2c_client *client)
 		return -EINVAL;
 	}
 
-	rk808->i2c = client;
+	rk808->dev = &client->dev;
 	i2c_set_clientdata(client, rk808);
 
 	rk808->regmap = devm_regmap_init_i2c(client, rk808->regmap_cfg);

include/linux/mfd/rk808.h

@@ -787,7 +787,7 @@ enum {
 };
 
 struct rk808 {
-	struct i2c_client		*i2c;
+	struct device			*dev;
 	struct regmap_irq_chip_data	*irq_data;
 	struct regmap			*regmap;
 	long				variant;