i2c: Fix conditional for substituting empty ACPI functions

Add IS_ENABLED(CONFIG_I2C) to the conditional around a bunch of ACPI
functions.

The conditional around these functions depended only on CONFIG_ACPI.
But the functions are implemented in I2C core, so are only present if
CONFIG_I2C is enabled.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

include/linux/i2c.h

@@ -1066,7 +1066,7 @@ static inline int of_i2c_get_board_info(struct device *dev,
 struct acpi_resource;
 struct acpi_resource_i2c_serialbus;
 
-#if IS_ENABLED(CONFIG_ACPI)
+#if IS_ENABLED(CONFIG_ACPI) && IS_ENABLED(CONFIG_I2C)
 bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
 			       struct acpi_resource_i2c_serialbus **i2c);
 int i2c_acpi_client_count(struct acpi_device *adev);