mtd erase needs to be aligned with erase blocks. Use padded image size
for erasing the production volume.
As the environment grew above the current size of 0x1000 bytes by
introducing the new padding function, increase the env size to 0x4000.
While at it, clean up reset button function to work to more reliable on
that board.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
af3a1adee0