arm64: zynqmp: enable u-boot itb generation via binman if SPL is enabled

arm64: zynqmp: enable u-boot itb generation via binman if SPL is enabled

Output images are generated via Binman only if SPL is enabled, as
there is no consumer for them otherwise. An #ifdef check ensures that
when SPL is enabled, Binman generates the U-Boot ITB. If SPL is disabled,
ITB generation is skipped since the ITB format is supported only by SPL.
Without SPL, generating such an image is unnecessary, as it would not be
used

The second reason is that when a DTB is passed, the current logic cannot
handle it without an additional step in U-Boot to parse an appended FIT
image and enable board-specific code to select the correct DTB config.
The MULTI_DTB_FIT configuration should be used if support for multiple
DTBs is required, but SPL is not being used.

Signed-off-by: Prasad Kummari <prasad.kummari@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/7cba738ae36dacf7d1b0cfbaf13e0c9b3a0df225.1737462296.git.michal.simek@amd.com