iio: accel: add Freescale MMA7455L/MMA7456L 3-axis accelerometer driver

Add support for Freescale MMA7455L/MMA7456L 3-axis in 10-bit mode for
I2C and SPI bus. This rather simple driver that currently doesn't
support all the hardware features of MMA7455L/MMA7456L.

Tested on Embedded Artist's LPC4357 Dev Kit with MMA7455L on I2C bus.

Data sheets for the two devices can be found here:
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA7455L.pdf
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA7456L.pdf

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/mma7455.h

@@ -0,0 +1,19 @@
+/*
+ * IIO accel driver for Freescale MMA7455L 3-axis 10-bit accelerometer
+ * Copyright 2015 Joachim Eastwood <manabian@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MMA7455_H
+#define __MMA7455_H
+
+extern const struct regmap_config mma7455_core_regmap;
+
+int mma7455_core_probe(struct device *dev, struct regmap *regmap,
+		       const char *name);
+int mma7455_core_remove(struct device *dev);
+
+#endif