kernel-itbimage: set dtb load line only if DTB_LOAD is set
The load address line for the dtb should only be given if DTB_LOAD was
set accordingly before. Therefore add this check.
Without this patch the dtb was loaded to 0x0 if no DTB_LOAD was set and
the boot therefore failed. Now when no DTB_LOAD is set the bootloader
uses the device tree in place.
Signed-off-by: Richard Leitner <richard.leitner@skidata.com> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
