Patch merged into coreboot/master: mainboard/google/snappy: Tune i2c frequency to 400 Khz

the following patch was just integrated into master:
commit 1612cef81f20cb955d591f3cebcf864d784856ac
Author: Wisley Chen 
Date:   Sun Nov 27 16:56:30 2016 +0800

mainboard/google/snappy: Tune i2c frequency to 400 Khz

tune i2c devices clk for snappy:
    I2C0: audio
    I2C2: TPM H1
    I2C3: elan touchscreen
    I2C4: elan touchpad
    I2C5: wacom digitizer

BUG=chrome-os-partner:59034
    BRANCH=master
    TEST=emerge-snappy coreboot chromeos-bootimage, and measured on EVT.
    audio:
      Freq. 393.7kHz
      Rise Time 58.8ns
      Fall time 12.11ns
    TPM H1:
      Freq. 398.8kHz
      Rise Time 31.71ns
      Fall time 13.28ns
    elan touchscreen:
      Freq. 390.5kHz
      Rise Time 235.7ns
      Fall time 37.64ns
    elan touchpad:
      Freq. 393.7kHz
      Rise Time 288.8ns
      Fall time 51.67ns
    wacom digitizer:
      Freq. 388.8kHz
      Rise Time 124.1ns
      Fall time 21.10ns

Change-Id: Ib2be9e1575d4962476423eafa80f9bb10ba40e17
    Signed-off-by: Wisley Chen 
    Reviewed-on: https://review.coreboot.org/17634
    Reviewed-by: Aaron Durbin 
    Tested-by: build bot (Jenkins)

See https://review.coreboot.org/17634 for details.

-gerrit