mb/google/sarien: Modify ELAN Touchpad i2c bus clk

Modify ELAN touchpad bus i2c clk from 466Khz to 400Khz.

BUG=b:119628524
BRANCH=master
TEST=measure ELAN Touchpad CLK

Change-Id: Ia8433c6ef320cea9a0145db4ba440d67ccd0f41e
Signed-off-by: John Su <john_su@compal.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/30588
Reviewed-by: Lijian Zhao <lijian.zhao@intel.com>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/sarien/variants/sarien/devicetree.cb

@@ -74,8 +74,8 @@ chip soc/intel/cannonlake
 		},
 		.i2c[1] = {
 			.speed = I2C_SPEED_FAST,
-			.rise_time_ns = 290,
-			.fall_time_ns = 110,
+			.rise_time_ns = 176,
+			.fall_time_ns = 15,
 		},
 		.i2c[4] = {
 			.early_init = 1,