am33xx: fix compiler warning in board_identify

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
arm: revert NAND init changes

- revert changes board specific NAND init introduced in
  463c9de7d0e903132ba8ebff72db6d5404de3f04

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
nand: disable NAND init for piA-AM335x_MMI in driver

- initializing non-existing NAND causes u-boot to freeze

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia335x: show board name in detection routine

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia335x: add nand configuration with 4k page size

- activated by #defining NAND_4K_PAGES
- configuration for Micron NAND devices with 4K page and 256K block size

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia335x: disable testing routines in SPL

- don't waste space with unused function for SPL

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia335x: enable USB support in SPL

- allows booting via USB RNDIS

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia335x: rename E2 config and add board definitions for piA-AM335x

- E2 is a special board type, mark it as such
- piA-AM335x is supposed to be the generic pironex board

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>