Merge branch 'master' of git://git.denx.de/u-boot-nds32

* 'master' of git://git.denx.de/u-boot-nds32:
  nds32: asm/io.h: add __iormb __iowmb and inline io support
  nds32: cache: define ARCH_DMA_MINALIGN for DMA buffer alignment
  nds32: Use getenv_ulong() in place of getenv(), strtoul