staging: iio: adis16209: Remove mutex_lock() and mutex_unlock() calls

The function adis16209_read_raw() is safe to be run in parallel.
The call to adis_read_reg_16() is safe since adis_read_reg() uses the
txrx_lock from struct adis to protect simultaneous changes.

Remove mutex.h inclusion since it is no longer needed.
Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/accel/adis16209.c

@@ -7,7 +7,6 @@
  */
 
 #include <linux/delay.h>
-#include <linux/mutex.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/spi/spi.h>
@@ -254,17 +253,14 @@ static int adis16209_read_raw(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
-		mutex_lock(&indio_dev->mlock);
 		addr = adis16209_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;
 	}
 	return -EINVAL;