cmd: bind: Use device sequence instead for driver bind/unbind

Currently uclass index is used for bind/unbind which ignores alias
sequence numbering. Use device sequence number instead as it's
the number explicitly set in the DT.

Also update documentation to use sequence number.

Signed-off-by: Zixun LI <admin@hifiphile.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
3 files changed