staging: iio: adis16240: Remove mutex_lock() and mutex_unlock() function call.

Remove mutex_lock() and mutex_unlock() function calls, as the
adis16240_spi_read_signed() function can be run parallel and safely
multiple times. Also remove the mutex.h header file and comment, which
are no longer required.

As indio_dev is declared and initialized in adis16240_spi_read_signed(),
again declaration to same type and initialization to same value is not
required, remove it from adis16240_read_12bit_signed().

Simplify the return logic, by merging assignment and return into a single
line.

Signed-off-by: Varsha Rao <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/accel/adis16240.c

···
 #include <linux/irq.h>
 #include <linux/gpio.h>
 #include <linux/delay.h>
-#include <linux/mutex.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/spi/spi.h>
···
 					   struct device_attribute *attr,
 					   char *buf)
 {
-	ssize_t ret;
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-
-	/* Take the iio_dev status lock */
-	mutex_lock(&indio_dev->mlock);
-	ret =  adis16240_spi_read_signed(dev, attr, buf, 12);
-	mutex_unlock(&indio_dev->mlock);
-
-	return ret;
+	return adis16240_spi_read_signed(dev, attr, buf, 12);
 }
 
 static IIO_DEVICE_ATTR(in_accel_xyz_squared_peak_raw, 0444,
···
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_CALIBBIAS:
 		bits = 10;
-		mutex_lock(&indio_dev->mlock);
 		addr = adis16240_addresses[chan->scan_index][0];
 		ret = adis_read_reg_16(st, addr, &val16);
 		if (ret) {
-			mutex_unlock(&indio_dev->mlock);
 			return ret;
 		}
 		val16 &= (1 << bits) - 1;
 		val16 = (s16)(val16 << (16 - bits)) >> (16 - bits);
 		*val = val16;
-		mutex_unlock(&indio_dev->mlock);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_PEAK:
 		bits = 10;
-		mutex_lock(&indio_dev->mlock);
 		addr = adis16240_addresses[chan->scan_index][1];
 		ret = adis_read_reg_16(st, addr, &val16);
 		if (ret) {
-			mutex_unlock(&indio_dev->mlock);
 			return ret;
 		}
 		val16 &= (1 << bits) - 1;
 		val16 = (s16)(val16 << (16 - bits)) >> (16 - bits);
 		*val = val16;
-		mutex_unlock(&indio_dev->mlock);
 		return IIO_VAL_INT;
 	}
 	return -EINVAL;