google/rambi: add explicit pull-down for ram-id

Some variants need the internal pull resistor on GPIO_SSUS_40
set explicitly to pull down rather than disabling the pull,
in order for the ram-id to be read correctly via GPIO.

Correct this by adding a function to enable and set the internal pull
and define its use as needed in the board's variant.h.

Chromium source:
branch: firmware-gnawty-5216.239.B
/src/soc/intel/baytrail/baytrail/gpio.h#418
/src/mainboard/google/gnawty/romstage.c#60

Test: boot 4GB Candy board and observe correct RAM id, amount detected

Change-Id: I8823c27385f4422184b5afa57f6048f7ff2a25ab
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/18309
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

0 files changed, 0 insertions, 0 deletions