arm, am335x: Updates and fixes for all 3 siemens boards

all:
    - Unified environment variables for siemens boards.
    - Factory set pid and vid defaults are used when no entry is
      found in eeprom. Removing of DEVid and other display
      parameters since not used. DEVid is not set as env variable
      anymore.
    - Boot menu is only entered if <Esc><Esc> is pressed.
    - Rename partitions showed in dfu mode. Nand partitions are now
      back to lower case as in initial version.
    - Load mtdparts on network boot.
    - Removed duplicate defines and compiler warnings, fix coding style

dxr2:
    - Two ddr3 parameters added and shadow registers removed.
      Printing of ddr3 parameters only in spl. ddr3 version number
      incremented.
    - Size of chip_data increased by 1 byte. TI's device nomenclature
      demands a string of up to 15 characters. sdevname needs thus
      to hold 16 characters.

pxm2 & rut:
    - Fix the u-boot environment variables to make mmc boot work.

Signed-off-by: Samuel Egli <samuel.egli@siemens.com>
Cc: Pascal Bach <pascal.bach@siemens.com>
Cc: Roger Meier <r.meier@siemens.com>
build U-Boot on Travis CI - https://travis-ci.org/

Signed-off-by: Roger Meier <roger@bufferoverflow.ch>