ectool: Allow for chips with more than 1 MB of flash
ectool: Allow for chips with more than 1 MB of flash

ectool currently assumes any offset >= 0x100000 (1MB) is invalid,
this is not true on STM32H7.

BRANCH=none
BUG=none
TEST=ectool --name=cros_fp flasherase 0x120000 131072 does not fail
     with "Bad offset."

Change-Id: I5f8e29b03dbc4c1a3f1566b0e78d4466f4a44565
Signed-off-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1139951
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec