ARM: pia335x: fix UART0 pin muxing

- UART0 was not correctly initialized
- EEPROM has not been read yet even though we tried to mux based on the
  board id

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
ARM: pia335x: disable evm check for default MPU PLL freq

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
ARM: pia335x: enable NAND init only for E2 variant of the board

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