clients: close unused keymap fd
In the simple examples in which keymap is not handled, the open descriptor has to be properly closed.
After each suspend/resume sequence the keymap is send again to every client. On client weston-simple-egl the leak causes a segfault when no more file descriptors can be opened.
Close the file descriptor and lazily copy/paste the comment already available in simple-dmabuf-v4l.
Signed-off-by: Antonio Borneo email@example.com