input: misc: keychord: move header to uapi

Move the entire contents of linux/keychord.h header to uapi, it only
contains a userspace interface.

Change-Id: If94f83328b19efb58c66391dce3bd8e927788d8d
Signed-off-by: Colin Cross <ccross@android.com>
Git-commit: 3a7a4898998bc2d47bafd362da30df59374e2669
Git-Repo: https://android.googlesource.com/kernel/common.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>