mfd: Separate out STMPE controller and interface specific code

Few STMPE controller can have register interface over SPI or I2C. Current
implementation only supports I2C and all code is present in a single file
stmpe.c. It would be better to separate out I2C interface specific code from
controller specific code. Later SPI specific code can be added in a separate
file.

This patch separates out I2C and controller specific code into separate files,
making stmpe.c independent of I2C.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/include/linux/mfd/stmpe.h b/include/linux/mfd/stmpe.h
index 270d661..babc6b2 100644
--- a/include/linux/mfd/stmpe.h
+++ b/include/linux/mfd/stmpe.h
@@ -50,13 +50,15 @@
 
 
 struct stmpe_variant_info;
+struct stmpe_client_info;
 
 /**
  * struct stmpe - STMPE MFD structure
  * @lock: lock protecting I/O operations
  * @irq_lock: IRQ bus lock
  * @dev: device, mostly for dev_dbg()
- * @i2c: i2c client
+ * @client: client - i2c or spi
+ * @ci: client specific information
  * @partnum: part number
  * @variant: the detected STMPE model number
  * @regs: list of addresses of registers which are at different addresses on
@@ -72,7 +74,8 @@
 	struct mutex lock;
 	struct mutex irq_lock;
 	struct device *dev;
-	struct i2c_client *i2c;
+	void *client;
+	struct stmpe_client_info *ci;
 	enum stmpe_partnum partnum;
 	struct stmpe_variant_info *variant;
 	const u8 *regs;