- dscc4_patch_register() turns into scc_patchl() and should now avoid an
  hardware bug quoted in errata sheet;
- dscc4_init_registers() interface changes as any caller doesn't really need
  to poke into dscc4_dev_priv internal;
- scc_{writel/readl}() are added to access some buggy behaving registers;
- {read/write}l conversion to the previous functions
- dscc4_do_tx() sneaks, sorry. Belongs to HOLD -> LxDA changes.