common/keyboard_8042: Add ability to specify 8042 channel
common/keyboard_8042: Add ability to specify 8042 channel

We actually have two data channels we can send data on. This CL only
adds the functionality to specify the additional channel. We only define
the KBD channel for now. A follow up will add the AUX channel.

BUG=b:145575366
BRANCH=none
TEST=Verified keyboard data is still sent

Change-Id: Icaed0a741cee4dac5eb5e6f36bd4e45d4a1e1bcd
Signed-off-by: Raul E Rangel <9a9c998e11a2655b1de9a05eeeef5f710c0dc7ed@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2073285
Reviewed-by: Edward Hill <db1406b34e091703092b6b136bdfeb2c8125fc0e@chromium.org>

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