arm,davinci: update for enbw_cmc board

- change gpio pin settings:

  - gpio pin 6[13] (PLC reset) default value low
  - gpio pin 6[0] (TPM reset) default value low
  - 4 new GPIO pins
      pin  i/o   name
    - 3[9] input Board Type
    - 2[7] input HW-ID0
    - 2[6] input HW-ID1
    - 2[3] input HW-ID2

- read board type and hw id from gpio pins on the enbw_cmc board,
  and use board type for setting up different gpio pin settings.

- do not pass "davinci_mmc.use_dma=0" to linux, as MMC now
  works with DMA.

- update logbuf support:
  store post word in RTC scratch register

- add support for configuring KSZ8864RMN switch through
  a config file on u-boot startup. For more infos see:
  doc/README.switch_config

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Tom Rini <tom.rini@gmail.com>
Cc: Christian Riesch <christian.riesch@omicron.at>
Cc: Sandeep Paulraj <s-paulraj@ti.com>