mainboard/google/reef: increase trackpad data hold time

Even though the i2c spec has no minimum data hold time in fast
mode the trackpad vendor indicates 300ns is their minimum. However,
the topology of the board uses FET isolation to cross voltage
domains. Therefore, the default 300ns which should work isn't reflected
on the device side of the voltage isolation circuit. Therefore,
increase the data hold time to show an observed data hold time of
more than 300ns on the device side.

BUG=b:36469182

Change-Id: I1b70f2f53c5a29cc7cfd5035a71ca5811b3bcba0
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/19065
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/reef/variants/baseboard/devicetree.cb

@@ -103,6 +103,7 @@ chip soc/intel/apollolake
 		.speed = I2C_SPEED_FAST,
 		.rise_time_ns = 114,
 		.fall_time_ns = 164,
+		.data_hold_time_ns = 350,
 	}"
 
 	# digitizer at 400kHz