This PR adds support for the StarFive JH7110 RISC-V SoC. This will be used by the upcoming port of NuttX for PINE64 Star64 SBC. [The source files are explained in the articles here](https://github.com/lupyuen/nuttx-star64)
Modified Files in arch/risc-v:
Kconfig: Added ARCH_CHIP_JH7110 for JH7110 SoC
New Files in arch/risc-v:
include/jh7110/chip.h: JH7110 Definitions
include/jh7110/irq.h: Support 127 External Interrupts
src/jh7110/chip.h: Interrupt Stack Macro
src/jh7110/jh7110_allocateheap.c: Kernel Heap
src/jh7110/jh7110_head.S: Linux Header and Boot Code
src/jh7110/jh7110_irq.c: Configure Interrupts
src/jh7110/jh7110_irq_dispatch.c: Dispatch Interrupts
src/jh7110/jh7110_memorymap.h: Memory Map
src/jh7110/jh7110_mm_init.c, jh7110_mm_init.h: Memory Mgmt
src/jh7110/jh7110_pgalloc.c: Page Allocator
src/jh7110/jh7110_start.c: Startup Code
src/jh7110/jh7110_timerisr.c: Timer Interrupt
src/jh7110/hardware/jh7110_memorymap.h: PLIC Base Address
src/jh7110/hardware/jh7110_plic.h: PLIC Register Addresses
src/jh7110/Kconfig: JH7110 Config
src/jh7110/Make.defs: Makefile
