bootstd: Allow display of the x86 setup information

Provide an option to dump this information if available.

Move the funciion prototype to the common x86 header. Allow the command
line to be left out since 'bootflow info' show this itself and it is
not in the correct place in memory until the kernel is actually booted.

Fix a badly aligned heading while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>