ec/lenovo/h8: Clear EC output queue before enablement

Sometimes (observed on Thinkpad T400s during cold boot) a few (only one
observed) garbage bytes may detained in the output queue of EC after power
up, and they should be cleared otherwise later communications will be
disrupted.

Change-Id: Id1733f7350232d0b10ac0d1bc912b62e7fa4da75
Signed-off-by: Bill XIE <persmule@gmail.com>
Reviewed-on: https://review.coreboot.org/22181
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maximilian Schander <coreboot@mimoja.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
1 file changed