pia-am335x: fix DDR initialization for piA-AM335x...

- revert BeagleBone testing code which enabled DDR2 mode
- piA-AM335x boards use DDR3 memory only

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am355x: add new pm baseboards to board_is_pia()

- we use a different naming scheme for piA-AM335x-PM Baseboards
- add the new name prefix to board_is_pia()

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-eb-tft: implement default pinmux for EB_TFT_Baseboard

- based on PM pinmux and EB_TFT changes

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-eb-tft: enable CPSW initialization

- EB_TFT is using MII2, do initialization the same way as for E2

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