udelay.c: Enable providing delay calibration value through CLI

This commit implements --loop-delay option to retrieve and provide the
calibration loop delay through the command line. The delay calibration
procedure can take up to few seconds, which adds up when executed a
number of times consecutively.  Therefore, this provides a means to
execute it only once, and then re-use the calibrated value on
subsequent runs. Also, it implements a sanity check, expecting the
value to land within 10% of the theoretical delay expectance,
otherwise it ignores the provided value and runs the calibration
procedure instead.

        modified:   cli_classic.c
        modified:   flashrom.8.tmpl
        modified:   programmer.h
        modified:   udelay.c

Change-Id: Iea2a7f62300663bc0a32ed4abced57c8c55c90c8
Signed-off-by: Hrvoje Cavrak <hrvoje@hrvoje.org>
---
M cli_classic.c
M flashrom.8.tmpl
M programmer.h
M udelay.c
4 files changed, 52 insertions(+), 3 deletions(-)