If adding a header to a .hex file (using the command line
"--pad-header"), the hex file gets shifted by header size. This may
cause hard coded addresses to be off by "header-size", making the
firmware unusable. Instead, adjust the base address by the header
size, so the existing firmware in the hex file is loaded to the
proper addresses.
Signed-off-by: Mark Schulte <mschulte@lyft.com>