soc/mediatek/i2c: Return negative values on error

Following coreboot's convention, return negative error codes from
platform_i2c_transfer().

BUG=none
TEST=emerge-asurada coreboot
BRANCH=none

Change-Id: I955b9aae11e20d75fac414d15714330e364dad2f
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59539
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

0 files changed, 0 insertions, 0 deletions