MFC r260695, r260696, r260884, r260885, r260886, r260887

  Provide a simplified way to specify GPIO pins for the Atmel port.

  Add at91 data so we can convert a PIO unit number into a base address.

  Add at91 standard memory controller helper functions.

  Generalize AT91 NAND support a bit.

  Connect NAND for the SAM9260EK eval board, as well as the HotE HL-201.

  Add nand device and NANDFS into the mix for those at91 boards that have
  support for it at the moment.
MFC r259728, r260752

  Add Freescale i.MX515 vt(9) driver.