uc_stm32h7_can:Correct initalization of the mumber of interfaces

H7 Only supports 2 not 3 CAN interfaces.

   CanInitHelper passes in in the run time configuration of
   the number of interfaces. The code was ignoring these!

src/drivers/uavcan/uavcan_drivers/stm32h7/driver/include/uavcan_stm32h7/can.hpp

@@ -261,7 +261,7 @@ public:
 #else
 		, num_ifaces_(1)
 #endif
-		, enabledInterfaces_(0x7)
+		, enabledInterfaces_(0x3)
 	{
 		uavcan::StaticAssert < (RxQueueCapacity <= CanIface::MaxRxQueueCapacity) >::check();
 	}

src/drivers/uavcan/uavcan_drivers/stm32h7/driver/src/uc_stm32h7_can.cpp

@@ -1032,6 +1032,8 @@ int CanDriver::init(const uavcan::uint32_t bitrate, const CanIface::OperatingMod
 {
 	int res = 0;
 
+	enabledInterfaces_ = enabledInterfaces;
+
 	UAVCAN_STM32H7_LOG("Bitrate %lu mode %d", static_cast<unsigned long>(bitrate), static_cast<int>(mode));
 
 	static bool initialized_once = false;
@@ -1045,7 +1047,8 @@ int CanDriver::init(const uavcan::uint32_t bitrate, const CanIface::OperatingMod
 	/*
 	 * FDCAN1
 	 */
-	if (enabledInterfaces & 1) {
+	if (enabledInterfaces_ & 1) {
+		num_ifaces_ = 1;
 		UAVCAN_STM32H7_LOG("Initing iface 0...");
 		ifaces[0] = &if0_;                          // This link must be initialized first,
 		res = if0_.init(bitrate, mode);             // otherwise an IRQ may fire while the interface is not linked yet;
@@ -1062,7 +1065,8 @@ int CanDriver::init(const uavcan::uint32_t bitrate, const CanIface::OperatingMod
 	 */
 #if UAVCAN_STM32H7_NUM_IFACES > 1
 
-	if (enabledInterfaces & 2) {
+	if (enabledInterfaces_ & 2) {
+		num_ifaces_ = 2;
 		UAVCAN_STM32H7_LOG("Initing iface 1...");
 		ifaces[1] = &if1_;                          // Same thing here.
 		res = if1_.init(bitrate, mode);