Documentation/features: Add csky kernel features

Documentation/features: Add csky kernel features

      core/ cBPF-JIT             : TODO |
      core/ eBPF-JIT             : TODO |
      core/ generic-idle-thread  :  ok  |
      core/ jump-labels          : TODO |
      core/ tracehook            :  ok  |
     debug/ KASAN                : TODO |
     debug/ gcov-profile-all     : TODO |
     debug/ kgdb                 : TODO |
     debug/ kprobes-on-ftrace    : TODO |
     debug/ kprobes              : TODO |
     debug/ kretprobes           : TODO |
     debug/ optprobes            : TODO |
     debug/ stackprotector       : TODO |
     debug/ uprobes              : TODO |
     debug/ user-ret-profiler    : TODO |
        io/ dma-contiguous       :  ok  |
   locking/ cmpxchg-local        : TODO |
   locking/ lockdep              : TODO |
   locking/ queued-rwlocks       :  ok  |
   locking/ queued-spinlocks     : TODO |
   locking/ rwsem-optimized      : TODO |
      perf/ kprobes-event        : TODO |
      perf/ perf-regs            : TODO |
      perf/ perf-stackdump       : TODO |
     sched/ membarrier-sync-core : TODO |
     sched/ numa-balancing       :  ..  |
   seccomp/ seccomp-filter       : TODO |
      time/ arch-tick-broadcast  : TODO |
      time/ clockevents          :  ok  |
      time/ context-tracking     : TODO |
      time/ irq-time-acct        : TODO |
      time/ modern-timekeeping   :  ok  |
      time/ virt-cpuacct         : TODO |
        vm/ ELF-ASLR             : TODO |
        vm/ PG_uncached          : TODO |
        vm/ THP                  :  ..  |
        vm/ batch-unmap-tlb-flush: TODO |
        vm/ huge-vmap            : TODO |
        vm/ ioremap_prot         : TODO |
        vm/ numa-memblock        :  ..  |
        vm/ pte_special          : TODO |

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>