src/platforms: move all headers to platforms/common/include/px4_platform_common

and remove the px4_ prefix, except for px4_config.h.

command to update includes:
for k in app.h atomic.h cli.h console_buffer.h defines.h getopt.h i2c.h init.h log.h micro_hal.h module.h module_params.h param.h param_macros.h posix.h sem.h sem.hpp shmem.h shutdown.h tasks.h time.h workqueue.h; do for i in $(grep -rl 'include <px4_'$k src platforms boards); do sed -i 's/#include <px4_'$k'/#include <px4_platform_common\/'$k/ $i; done; done
for in $(grep -rl 'include <px4_config.h' src platforms boards); do sed -i 's/#include <px4_config.h/#include <px4_platform_common\/px4_config.h'/ $i; done

Transitional headers for submodules are added (px4_{defines,log,time}.h)

platforms/posix/src/px4/common/px4_sem.cpp

@@ -37,9 +37,9 @@
  * PX4 Middleware Wrapper Linux Implementation
  */
 
-#include <px4_defines.h>
-#include <px4_workqueue.h>
-#include <px4_time.h>
+#include <px4_platform_common/defines.h>
+#include <px4_platform_common/workqueue.h>
+#include <px4_platform_common/time.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <pthread.h>
@@ -47,7 +47,7 @@
 
 #if (defined(__PX4_DARWIN) || defined(__PX4_CYGWIN) || defined(__PX4_POSIX)) && !defined(__PX4_QURT)
 
-#include <px4_posix.h>
+#include <px4_platform_common/posix.h>
 
 int px4_sem_init(px4_sem_t *s, int pshared, unsigned value)
 {