hwmon: (lm75) Add STLM75 support

The STLM75 is a high-precision digital CMOS temperature sensor
IC with a sigma-delta temperature-to-digital converter.

The configuration register mapping is similar to existing lm75
but the sample rate is 150ms(max).

Tested on real hardware and verified temperature readings are correct.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/lm75

@@ -42,6 +42,11 @@ Supported chips:
     Addresses scanned: none
     Datasheet: Publicly available at the ST website
                http://www.st.com/internet/analog/product/121769.jsp
+  * ST Microelectronics STLM75
+    Prefix: 'stlm75'
+    Addresses scanned: none
+    Datasheet: Publicly available at the ST website
+	       https://www.st.com/resource/en/datasheet/stlm75.pdf
   * Texas Instruments TMP100, TMP101, TMP105, TMP112, TMP75, TMP75C, TMP175, TMP275
     Prefixes: 'tmp100', 'tmp101', 'tmp105', 'tmp112', 'tmp175', 'tmp75', 'tmp75c', 'tmp275'
     Addresses scanned: none

drivers/hwmon/Kconfig

@@ -1035,6 +1035,7 @@ config SENSORS_LM75
 		- National Semiconductor LM75, LM75A
 		- NXP's LM75A
 		- ST Microelectronics STDS75
+		- ST Microelectronics STLM75
 		- TelCom (now Microchip) TCN75
 		- Texas Instruments TMP100, TMP101, TMP105, TMP112, TMP75,
 		  TMP175, TMP275

drivers/hwmon/lm75.c

@@ -50,6 +50,7 @@ enum lm75_type {		/* keep sorted in alphabetical order */
 	max31725,
 	mcp980x,
 	stds75,
+	stlm75,
 	tcn75,
 	tmp100,
 	tmp101,
@@ -316,6 +317,10 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		data->resolution = 11;
 		data->sample_time = MSEC_PER_SEC;
 		break;
+	case stlm75:
+		data->resolution = 9;
+		data->sample_time = MSEC_PER_SEC / 5;
+		break;
 	case ds7505:
 		set_mask |= 3 << 5;		/* 12-bit mode */
 		data->resolution = 12;
@@ -424,6 +429,7 @@ static const struct i2c_device_id lm75_ids[] = {
 	{ "max31726", max31725, },
 	{ "mcp980x", mcp980x, },
 	{ "stds75", stds75, },
+	{ "stlm75", stlm75, },
 	{ "tcn75", tcn75, },
 	{ "tmp100", tmp100, },
 	{ "tmp101", tmp101, },
@@ -494,6 +500,10 @@ static const struct of_device_id lm75_of_match[] = {
 		.compatible = "st,stds75",
 		.data = (void *)stds75
 	},
+	{
+		.compatible = "st,stlm75",
+		.data = (void *)stlm75
+	},
 	{
 		.compatible = "microchip,tcn75",
 		.data = (void *)tcn75