Replacing usleep with px4_usleep

This is a step towards isolating time from the system.

src/lib/cdev/posix/cdev_platform.cpp

@@ -340,7 +340,7 @@ extern "C" {
 #endif
 
 		while (sim_delay) {
-			usleep(100);
+			px4_usleep(100);
 		}
 
 		PX4_DEBUG("Called px4_poll timeout = %d", timeout);

src/lib/cdev/test/cdevtest_example.cpp

@@ -234,7 +234,7 @@ int CDevExample::do_poll(int fd, int timeout, int iterations, int delayms_after_
 		}
 
 		if (delayms_after_poll) {
-			usleep(delayms_after_poll * 1000);
+			px4_usleep(delayms_after_poll * 1000);
 		}
 
 		loop_count++;

src/lib/parameters/parameters.cpp

@@ -1280,7 +1280,7 @@ param_import_internal(int fd, bool mark_saved)
 
 	do {
 		result = bson_decoder_next(&decoder);
-		usleep(1);
+		px4_usleep(1);
 
 	} while (result > 0);
 

src/lib/rc/dsm.cpp

@@ -57,7 +57,7 @@
 #include <nuttx/arch.h>
 #define dsm_udelay(arg)    up_udelay(arg)
 #else
-#define dsm_udelay(arg) usleep(arg)
+#define dsm_udelay(arg) px4_usleep(arg)
 #endif
 
 // #define DSM_DEBUG