Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

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.

Generalize AT91 NAND support a bit. Be more flexible about ALE and CLE
address line assignment. Provide convenince function to set these things.