AP_HAL_Linux: use ARRAY_SIZE macro

libraries/AP_HAL_Linux/dsm.cpp

@@ -38,6 +38,9 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+
+#include <AP_Common.h>
+
 #include "dsm.h"
 
 #define DSM_FRAME_SIZE		16		/**<DSM frame size in bytes*/
@@ -159,7 +162,7 @@ dsm_guess_format(bool reset, const uint8_t dsm_frame[16])
 	unsigned votes10 = 0;
 	unsigned votes11 = 0;
 
-	for (unsigned i = 0; i < (sizeof(masks) / sizeof(masks[0])); i++) {
+	for (unsigned i = 0; i < ARRAY_SIZE(masks); i++) {
 
 		if (cs10 == masks[i])
 			votes10++;

libraries/AP_HAL_Linux/examples/BusTest/BusTest.cpp

@@ -40,7 +40,7 @@ void loop(void)
 
     hal.console->printf("Scanning SPI bus devices\n");
 
-    for (uint8_t i=0; i<sizeof(whoami_list)/sizeof(whoami_list[0]); i++) {
+    for (uint8_t i=0; i < ARRAY_SIZE(whoami_list); i++) {
         spi = hal.spi->device(whoami_list[i].dev);
         if (spi == NULL) {
             hal.console->printf("Failed to get SPI device for %s\n", whoami_list[i].name);