Pull nds32 updates from Greentime Hu:

 - Perf support

 - Power management support

 - FPU support

 - Hardware prefetcher support

 - Build error fixed

 - Performance enhancement

* tag 'nds32-for-linus-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux:
  nds32: support hardware prefetcher
  nds32: Fix the items of hwcap_str ordering issue.
  math-emu/soft-fp.h: (_FP_ROUND_ZERO) cast 0 to void to fix warning
  math-emu/op-2.h: Use statement expressions to prevent negative constant shift
  nds32: support denormalized result through FP emulator
  nds32: Support FP emulation
  nds32: nds32 FPU port
  nds32: Remove duplicated include from pm.c
  nds32: Power management for nds32
  nds32: Add document for NDS32 PMU.
  nds32: Add perf call-graph support.
  nds32: Perf porting
  nds32: Fix bug in bitfield.h
  nds32: Fix gcc 8.0 compiler option incompatible.
  nds32: Fill all TLB entries with kernel image mapping
  nds32: Remove the redundant assignment