CHROMIUM: atkbd: workaround for ChromeOS EC keyboard enable bug

CHROMIUM: atkbd: workaround for ChromeOS EC keyboard enable bug

The ChromeOS EC enables keystrokes too early, and the driver
can get scancodes when it's expecting a response from the
GETID request.  The workaround consists of repeating the request
a few times if it fails.

BUG=chrome-os-partner:17005
TEST=verified that the workaround works around the bug
BRANCH=none

Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Change-Id: Ica4ad7ed1564c07ab196b302d1a33732a48c680f
Reviewed-on: https://gerrit.chromium.org/gerrit/43049
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Tested-by: Luigi Semenzato <semenzato@chromium.org>
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>