A header used in ELECOM WRC-300GHBK2-I and WRC-1750GHBK2-I/C is also
used in ELECOM WRC-2533GHBK-I, so split the code to generate the header
and move it to image-commands.mk to use from ramips target.
Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>
Reviewed-by: Sungbo Eo <mans0n@gorani.run>
Signed-off-by: maurerr <mariusd84@gmail.com>