mb/google/octopus/variants/fleex: Adjust I2C0 CLK to meet spec

After adjustment on Grob360S
I2C0 CLK: 389.9 KHz

BUG=b:141729962
BRANCH=master
TEST=emerge-octopus coreboot chromeos-bootimage
     measure by scope with Grob360S.

Change-Id: I6a30257b7978cc8899a55f9fd6ffffe01cb2a851
Signed-off-by: John Su <john_su@compal.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35788
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: EricR Lai <ericr_lai@compal.corp-partner.google.com>

src/mainboard/google/octopus/variants/fleex/overridetree.cb

@@ -63,6 +63,8 @@ chip soc/intel/apollolake
 		},
 		.i2c[0] = {
 			.speed = I2C_SPEED_FAST,
+			.rise_time_ns = 25,
+			.fall_time_ns = 52,
 		},
 		.i2c[5] = {
 			.speed = I2C_SPEED_FAST,