scripts/make_fit: Speed up operation

scripts/make_fit: Speed up operation

The kernel is likely at least 16MB so we may as well use that as a step
size when reallocating space for the FIT in memory. Pack the FIT at the
end, so there is no wasted space.

This reduces the time to pack by an order of magnitude, or so.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://patch.msgid.link/20260106162738.2605574-2-sjg@chromium.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>