x86: cmd: hob: Fix the command usage and help messages

At present the hob command usage and help messages are messed up
in a single line. They should be separated.

This was a regression introduced when [seq] and [-v] were added
to the command.

Fixes: d11544df ("x86: hob: Add way to show a single hob entry")
Fixes: 51af144e ("x86: Allow showing details about a HOB entry")
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested on chromebook_coral, chromebook_samus, chromebook_link, minnowmax
Tested-by: Simon Glass <sjg@chromium.org>