make sure imx_sdp.c gets rebuilt on image.h change
make sure imx_sdp.c gets rebuilt on image.h change

Add image.h to the dependency list of imx_sdp.c

Signed-off-by: Stefan Agner <8bf81831f67286fff829779134e88c94b37210a1@toradex.com>

bwalle/imx_usb_loader,boundarydevices/imx_usb_loader