MFC r260118

  Delete echoed doesn't rub out the previous character, so always
  use <backspace> <space> <backspace> instead. This fixes hitting
  DELETE instead of BACKSPACE at mountroot> prompt.
MFC r260092, r260093, r260121, r260180,

  Allow AT91_MCI_ALLOW_OVERCLOCK to be an option in kernel config files.

  Set the SoC name for the atmelbus name.

  Add support for Samsung K9F2G08U0A (256MiB SLC) NAND

  Comment updates.