soraka: Ensure I2C5 frequency is less than 400kHz

Update I2C5 bus parameters to obtain clock frequency <400kHz.

BUG=b:65062416
TEST=Verified using an oscilloscope that I2C5 bus frequency
in factory is ~397kHz.

Change-Id: I3d0b0388343d4c6c5e7eabf3e06799d059307517
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/21669
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/poppy/variants/soraka/devicetree.cb

@@ -226,8 +226,8 @@ chip soc/intel/skylake
 		.speed = I2C_SPEED_FAST,
 		.speed_config[0] = {
 			.speed = I2C_SPEED_FAST,
-			.scl_lcnt = 180,
-			.scl_hcnt = 80,
+			.scl_lcnt = 195,
+			.scl_hcnt = 90,
 			.sda_hold = 36,
 		},
 	}"