cli_classic: Add convenient '--get-size' cli opt

We have this in the ChromiumOS fork of flashrom which we rely
on to obtain the current flash chip in use. This ports it for
upstream consumption.

This option prints the detected flashchips size such as in the case of:
 `flashrom -p internal --get-size`.
This is useful to validate we are using the right flash chip on a
multi-chip board for example or to correctly partition a chip up to
meet the detected size it provides.

V.2: Constrain number_of_operations to one as per Nico's comment.

Change-Id: I8f002f3b2012aec4d26b0e81456697b9a5de28d6
Signed-off-by: Edward O'Callaghan <quasisec@chromium.org>
---
M cli_classic.c
1 file changed, 17 insertions(+), 2 deletions(-)