HAL_Linux: Basic Zynq Linux platform support

Preliminary support for Zynq/Linux on the 'ZyboPilot' HW platform.

see https://github.com/trjw/ZyboPilot-bsp

 for the PetaLinux / Vivado project
files.

At this stage CPPM/Pulse in and PWM out work, and in CLI mode the passthru
test works correctly.

The platform has passed minimal smoke testing in HIL mode.

ZYNQ IS NOT FLIGHT TESTED YET!  FLY THIS PLATFORM AT YOUR OWN RISK!

Signed-off-by: John Williams <john@whelanwilliams.net>

libraries/AP_HAL_Linux/AP_HAL_Linux_Namespace.h

@@ -23,8 +23,10 @@ namespace Linux {
     class LinuxRCInput;
     class LinuxRCInput_PRU;
     class LinuxRCInput_Navio;
+    class LinuxRCInput_ZYNQ;
     class LinuxRCOutput_PRU;
     class LinuxRCOutput_Navio;
+    class LinuxRCOutput_ZYNQ;
     class LinuxSemaphore;
     class LinuxScheduler;
     class LinuxUtil;

libraries/AP_HAL_Linux/AP_HAL_Linux_Private.h

@@ -16,6 +16,7 @@
 #include "RCInput_Navio.h"
 #include "RCOutput_PRU.h"
 #include "RCOutput_Navio.h"
+#include "RCOutput_ZYNQ.h"
 #include "Semaphores.h"
 #include "Scheduler.h"
 #include "Util.h"

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -54,6 +54,8 @@ static Empty::EmptyGPIO gpioDriver;
 static LinuxRCInput_PRU rcinDriver;
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_NAVIO
 static LinuxRCInput_Navio rcinDriver;
+#elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ZYNQ
+static LinuxRCInput_ZYNQ rcinDriver;
 #else
 static LinuxRCInput rcinDriver;
 #endif
@@ -68,6 +70,8 @@ static LinuxRCOutput_PRU rcoutDriver;
  */
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_NAVIO
 static LinuxRCOutput_Navio rcoutDriver;
+#elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ZYNQ
+static LinuxRCOutput_ZYNQ rcoutDriver;
 #else
 static Empty::EmptyRCOutput rcoutDriver;
 #endif

libraries/AP_HAL_Linux/RCInput.h

@@ -59,5 +59,6 @@ public:
 };
 
 #include "RCInput_PRU.h"
+#include "RCInput_ZYNQ.h"
 
 #endif // __AP_HAL_LINUX_RCINPUT_H__