hwmon: (ltc2991) Add missing dependency on REGMAP_I2C

This driver requires REGMAP_I2C to be selected in order to get access to
regmap_config and devm_regmap_init_i2c. Add the missing dependency.

Fixes: 2b9ea426 ("hwmon: Add driver for ltc2991")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Message-ID: <20241002-hwmon-select-regmap-v1-3-548d03268934@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -1001,6 +1001,7 @@ config SENSORS_LTC2990
 config SENSORS_LTC2991
 	tristate "Analog Devices LTC2991"
 	depends on I2C
+	select REGMAP_I2C
 	help
 	  If you say yes here you get support for Analog Devices LTC2991
 	  Octal I2C Voltage, Current, and Temperature Monitor. The LTC2991