iio: imu: st_lsm6dsx: remove set but not used variable ''

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c: In function 'st_lsm6dsx_shub_read_reg':
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c:108:41: warning:
 variable 'hub_settings' set but not used [-Wunused-but-set-variable]

It never used since introduction in commit c91c1c84 ("iio: imu: st_lsm6dsx:
add i2c embedded controller support")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c

@@ -105,12 +105,10 @@ static void st_lsm6dsx_shub_wait_complete(struct st_lsm6dsx_hw *hw)
 static int st_lsm6dsx_shub_read_reg(struct st_lsm6dsx_hw *hw, u8 addr,
 				    u8 *data, int len)
 {
-	const struct st_lsm6dsx_shub_settings *hub_settings;
 	int err;
 
 	mutex_lock(&hw->page_lock);
 
-	hub_settings = &hw->settings->shub_settings;
 	err = st_lsm6dsx_set_page(hw, true);
 	if (err < 0)
 		goto out;