UAVCAN: Add STM32H7 FDCAN Driver

Took the existing uavcan_stm32 driver and replaced all bxCAN code with
the equivalent for FDCAN following ST Reference Manual RM0433.

Note: There is still a bug somewhere in regards to FDCAN2 (probably
incorrect setup of the message RAM? Not sure.)  But (FD)CAN1 is fully
functional (Classic CAN only, no CAN-FD).

Also TODO: Configure CAN filters.  Right now there are no filters; all
incoming messages are accepted.

boards/hex/cube-orange/default.cmake

@@ -10,7 +10,7 @@ px4_add_board(
 	BUILD_BOOTLOADER
 	IO px4_io-v2_default
 	TESTING
-	UAVCAN_INTERFACES 2 # - No H7 or FD can support in UAVCAN
+	UAVCAN_INTERFACES 2
 	SERIAL_PORTS
 		# IO DEBUG:/dev/ttyS0
 		TEL1:/dev/ttyS1
@@ -55,7 +55,7 @@ px4_add_board(
 		telemetry # all available telemetry drivers
 		test_ppm
 		tone_alarm
-#		uavcan - No H7 or FD can support in UAVCAN yet
+		uavcan
 	MODULES
 		airspeed_selector
 		attitude_estimator_q

boards/hex/cube-orange/nuttx-config/include/board.h

@@ -192,6 +192,9 @@
 #define STM32_RCC_D3CCIPR_SPI6SRC    RCC_D3CCIPR_SPI6SEL_PLL2    /* SPI6 clock source */
 #define STM32_RCC_D2CCIP2R_USBSRC    RCC_D2CCIP2R_USBSEL_PLL3    /* USB 1 and 2 clock source */
 #define STM32_RCC_D3CCIPR_ADCSEL     RCC_D3CCIPR_ADCSEL_PLL2     /* ADC 1 2 3 clock source */
+#define STM32_RCC_D2CCIP1R_FDCANSEL  RCC_D2CCIP1R_FDCANSEL_HSE   /* FDCAN 1 2 clock source */
+
+#define STM32_FDCANCLK               STM32_HSE_FREQUENCY
 
 /* FLASH wait states */
 #define BOARD_FLASH_WAITSTATES 2