Distribute sitl and board based assets for posix targets

This adds a src/board/<bebop|eagle|excelsior|rpi|sitl>/board_config.h
   to configure the build as is done with the Nuttx targets

   src/platforms/posix/include/board_config.h has been renamed to
   src/platforms/posix/include/system_config.h to allow the common
   posix defines to be included with the board specific defines.

src/platforms/posix/include/board_config.h

@@ -1,12 +0,0 @@
-
-/*
- * I2C busses
- */
-#define PX4_I2C_BUS_ESC		1
-#define PX4_SIM_BUS_TEST	2
-#define PX4_I2C_BUS_EXPANSION	3
-#define PX4_I2C_BUS_LED		3
-
-#define PX4_I2C_OBDEV_LED	0x55
-
-#define STM32_SYSMEM_UID "SIMULATIONID"

src/platforms/posix/include/system_config.h

@@ -0,0 +1,24 @@
+
+/*
+ * I2C busses
+ */
+#define PX4_I2C_BUS_ESC		1
+#define PX4_SIM_BUS_TEST	2
+#define PX4_I2C_BUS_EXPANSION	3
+#define PX4_I2C_BUS_LED		3
+
+#define PX4_I2C_OBDEV_LED	0x55
+
+#define STM32_SYSMEM_UID "SIMULATIONID"
+
+#define CONFIG_NFILE_STREAMS 1
+#define CONFIG_SCHED_WORKQUEUE 1
+#define CONFIG_SCHED_HPWORK 1
+#define CONFIG_SCHED_LPWORK 1
+#define CONFIG_ARCH_BOARD_SITL 1
+
+/** time in ms between checks for work in work queues **/
+#define CONFIG_SCHED_WORKPERIOD 50000
+
+#define CONFIG_SCHED_INSTRUMENTATION 1
+#define CONFIG_MAX_TASKS 32

src/platforms/px4_config.h

@@ -47,20 +47,6 @@
 #include "px4_micro_hal.h"
 
 #elif defined (__PX4_POSIX)
-
-#define CONFIG_NFILE_STREAMS 1
-#define CONFIG_SCHED_WORKQUEUE 1
-#define CONFIG_SCHED_HPWORK 1
-#define CONFIG_SCHED_LPWORK 1
-#define CONFIG_ARCH_BOARD_SITL 1
-
-#define BOARD_BATTERY1_V_DIV   (10.177939394f)
-#define BOARD_BATTERY1_A_PER_V (15.391030303f)
-
-/** time in ms between checks for work in work queues **/
-#define CONFIG_SCHED_WORKPERIOD 50000
-
-#define CONFIG_SCHED_INSTRUMENTATION 1
-#define CONFIG_MAX_TASKS 32
-
+#  include <system_config.h>
+#  include <board_config.h>
 #endif