asus-laptop: fix asus_input_init error path

This patch includes below fixes:
1. return -ENOMEM instead of 0 if input_allocate_device fail.
2. fix wrong goto if sparse_keymap_setup fail.
3. fix wrong goto if input_register_device fail.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>