tools, fit: add fit_info host command

add fit_info command to the host tools. This command prints
the name, offset and the len from a property from a node in
a fit file. This info can be used to extract a properties
data with linux tools, for example "dd".

Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Simon Glass <sjg@chromium.org>