initramfs.mk: move output instead of copying it.
initramfs.mk: move output instead of copying it.

Finally, it is a better idea to move output to super project so that it
is easier to redo the rule.

Signed-off-by: Gaël PORTAY <1666f60cfa201a60b0ea694168a0b6932673170a@gmail.com>

gazoo74/at91nandflash