reef_it8320: don't pull-up tx/rx of uart
reef_it8320: don't pull-up tx/rx of uart

Because H1 monitor tx/rx signals to detect servo board,
so we can't pull-up tx/rx or the DETECT_SERVO of H1 will
be always high even the servo board isn't connected.

BUG=none
BRANCH=none
TEST=H1 detect servo board correctly.

Change-Id: I2f2dfa220ed77478e6e622a0ed1189f559044aa3
Signed-off-by: Dino Li <338d523ecf3700bd86eb9c34d220f91911d2a18c@ite.com.tw>
Reviewed-on: https://chromium-review.googlesource.com/897315
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec