i2c: rework kernel config I2C_ACPI

Commit da3c6647(I2C/ACPI: Clean up I2C ACPI code and Add CONFIG_I2C_ACPI
config) adds a new kernel config I2C_ACPI and make I2C core built in
when the config is selected. This is wrong because distributions
etc generally compile I2C as a module and the commit broken that.
This patch is to rename I2C_ACPI to ACPI_I2C_OPREGION. New config
only controls ACPI I2C operation region code and depends on I2C=y.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: removed unrelated change for Kconfig]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/Makefile

@@ -3,7 +3,7 @@
 #
 
 i2ccore-y := i2c-core.o
-i2ccore-$(CONFIG_I2C_ACPI)	+= i2c-acpi.o
+i2ccore-$(CONFIG_ACPI)	 	+= i2c-acpi.o
 
 obj-$(CONFIG_I2C_BOARDINFO)	+= i2c-boardinfo.o
 obj-$(CONFIG_I2C)		+= i2ccore.o