staging: iio: hmc5843_core: fix sparse warnings

Fix the following sparse warnings:

 CHECK   drivers/staging/iio/magnetometer/hmc5843_core.c
drivers/staging/iio/magnetometer/hmc5843_core.c:138:70: warning:
incorrect type in argument 3 (different signedness)
drivers/staging/iio/magnetometer/hmc5843_core.c:138:70:    expected
unsigned int *val
drivers/staging/iio/magnetometer/hmc5843_core.c:138:70:    got int
*<noident>
drivers/staging/iio/magnetometer/hmc5843_core.c:215:64: warning:
incorrect type in argument 3 (different signedness)
drivers/staging/iio/magnetometer/hmc5843_core.c:215:64:    expected
unsigned int *val
drivers/staging/iio/magnetometer/hmc5843_core.c:215:64:    got int
*<noident>
drivers/staging/iio/magnetometer/hmc5843_core.c:354:72: warning:
incorrect type in argument 3 (different signedness)
drivers/staging/iio/magnetometer/hmc5843_core.c:354:72:    expected
unsigned int *val
drivers/staging/iio/magnetometer/hmc5843_core.c:354:72:    got int
*<noident>
drivers/staging/iio/magnetometer/hmc5843_core.c:362:72: warning:
incorrect type in argument 3 (different signedness)
drivers/staging/iio/magnetometer/hmc5843_core.c:362:72:    expected
unsigned int *val
drivers/staging/iio/magnetometer/hmc5843_core.c:362:72:    got int
*<noident>

Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/magnetometer/hmc5843_core.c

@@ -131,7 +131,7 @@ static s32 hmc5843_set_mode(struct hmc5843_data *data, u8 operating_mode)
 static int hmc5843_wait_measurement(struct hmc5843_data *data)
 {
 	int tries = 150;
-	int val;
+	unsigned int val;
 	int ret;
 
 	while (tries-- > 0) {
@@ -209,7 +209,7 @@ static ssize_t hmc5843_show_measurement_configuration(struct device *dev,
 						char *buf)
 {
 	struct hmc5843_data *data = iio_priv(dev_to_iio_dev(dev));
-	int val;
+	unsigned int val;
 	int ret;
 
 	ret = regmap_read(data->regmap, HMC5843_CONFIG_REG_A, &val);
@@ -344,7 +344,7 @@ static int hmc5843_read_raw(struct iio_dev *indio_dev,
 			    int *val, int *val2, long mask)
 {
 	struct hmc5843_data *data = iio_priv(indio_dev);
-	int rval;
+	unsigned int rval;
 	int ret;
 
 	switch (mask) {