doc: usage: DFU: Fix dfu_alt_info document

Fix some typo and wrong information about dfu_alt_info.
- Add the parameter format, decimal only or hexadecimal.
- Use same parameter name for the same kind of parameters.
  (e.g. dev -> dev_id)

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
1 file changed