sys/auto_init/saul: Fix some -Wsign-compare warnings

sys/auto_init/saul/auto_init_adc.c

@@ -55,7 +55,7 @@ extern saul_driver_t adc_saul_driver;
 void auto_init_adc(void)
 {
     DEBUG("auto init SAUL ADC\n");
-    for (int i = 0; i < SAUL_ADC_NUMOF; i++) {
+    for (unsigned int i = 0; i < SAUL_ADC_NUMOF; i++) {
         const saul_adc_params_t *p = &saul_adc_params[i];
         saul_adcs[i] = p;
 

sys/auto_init/saul/auto_init_gpio.c

@@ -53,7 +53,7 @@ extern saul_driver_t gpio_saul_driver;
 void auto_init_gpio(void)
 {
     DEBUG("auto init gpio SAUL\n");
-    for (int i = 0; i < SAUL_GPIO_NUMOF; i++) {
+    for (unsigned int i = 0; i < SAUL_GPIO_NUMOF; i++) {
         const saul_gpio_params_t *p = &saul_gpio_params[i];
 
         DEBUG("[auto_init_saul] initializing direct GPIO\n");

sys/auto_init/saul/auto_init_isl29020.c

@@ -51,7 +51,7 @@ extern saul_driver_t isl29020_saul_driver;
 
 void auto_init_isl29020(void)
 {
-    for (int i = 0; i < ISL29020_NUM; i++) {
+    for (unsigned int i = 0; i < ISL29020_NUM; i++) {
         const isl29020_params_t *p = &isl29020_params[i];
 
         DEBUG("[auto_init_saul] initializing isl29020 light sensor\n");

sys/auto_init/saul/auto_init_l3g4200d.c

@@ -51,7 +51,7 @@ extern saul_driver_t l3g4200d_saul_driver;
 
 void auto_init_l3g4200d(void)
 {
-    for (int i = 0; i < L3G4200D_NUM; i++) {
+    for (unsigned int i = 0; i < L3G4200D_NUM; i++) {
         const l3g4200d_params_t *p = &l3g4200d_params[i];
 
         DEBUG("[auto_init_saul] initializing l3g4200d gyroscope\n");

sys/auto_init/saul/auto_init_lis3dh.c

@@ -51,7 +51,7 @@ extern saul_driver_t lis3dh_saul_driver;
 
 void auto_init_lis3dh(void)
 {
-    for (int i = 0; i < LIS3DH_NUM; i++) {
+    for (unsigned int i = 0; i < LIS3DH_NUM; i++) {
         const lis3dh_params_t *p = &lis3dh_params[i];
         int res;
 

sys/auto_init/saul/auto_init_lps331ap.c

@@ -51,7 +51,7 @@ extern saul_driver_t lps331ap_saul_driver;
 
 void auto_init_lps331ap(void)
 {
-    for (int i = 0; i < LPS331AP_NUM; i++) {
+    for (unsigned int i = 0; i < LPS331AP_NUM; i++) {
         const lps331ap_params_t *p = &lps331ap_params[i];
 
         DEBUG("[auto_init_saul] initializing lps331ap pressure sensor\n");

sys/auto_init/saul/auto_init_lsm303dlhc.c

@@ -53,7 +53,7 @@ extern saul_driver_t lsm303dlhc_saul_mag_driver;
 
 void auto_init_lsm303dlhc(void)
 {
-    for (int i = 0; i < LSM303DLHC_NUM; i++) {
+    for (unsigned int i = 0; i < LSM303DLHC_NUM; i++) {
         const lsm303dlhc_params_t *p = &lsm303dlhc_params[i];
 
         DEBUG("[auto_init_saul] initializing lsm303dlhc acc/mag sensor\n");

sys/auto_init/saul/auto_init_mma8652.c

@@ -52,7 +52,7 @@ extern saul_driver_t mma8652_saul_driver;
 
 void auto_init_mma8652(void)
 {
-    for (int i = 0; i < MMA8652_NUM; i++) {
+    for (unsigned int i = 0; i < MMA8652_NUM; i++) {
         const mma8652_params_t *p = &mma8652_params[i];
 
         DEBUG("[auto_init_saul] initializing mma8652 acc sensor\n");