i2c: break out ACPI support into separate file

Removes some ifdeffery. Also add the new file to the relevant
MAINTAINERS section.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

MAINTAINERS

@@ -6273,6 +6273,7 @@ M:	Mika Westerberg <mika.westerberg@linux.intel.com>
 L:	linux-i2c@vger.kernel.org
 L:	linux-acpi@vger.kernel.org
 S:	Maintained
+F:	drivers/i2c/i2c-core-acpi.c
 
 I2C-TAOS-EVM DRIVER
 M:	Jean Delvare <jdelvare@suse.com>

drivers/i2c/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_I2C_BOARDINFO)	+= i2c-boardinfo.o
 obj-$(CONFIG_I2C)		+= i2c-core.o
 i2c-core-objs 			:= i2c-core-base.o i2c-core-smbus.o
+i2c-core-$(CONFIG_ACPI)		+= i2c-core-acpi.o
 i2c-core-$(CONFIG_I2C_SLAVE) 	+= i2c-core-slave.o
 i2c-core-$(CONFIG_OF) 		+= i2c-core-of.o