- This PR adds the LED Driver for QEMU RISC-V 32-bit and 64-bit (User LEDs and Auto LEDs)
- QEMU RISC-V LED Driver will be used by the Rust Blinky App for Google Summer of Code
- Blinking the LED is probably the most common Embedded Demo, and now it's supported by QEMU RISC-V
- We added NuttX Configs `rv-virt:leds` and `rv-virt:leds64` to support User LEDs for 32-bit and 64-bit RISC-V
- Turning on/off a Simulated User LED will print a log message: "LED 1 set to 1"
- The code is derived from NuttX PinePhone LED Driver
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