Merge patch series "Add support for secure falcon mode: disable fallback"

Anshul Dalal <anshuld@ti.com> says:

Continuing from the last series[1], this patch series addresses the requirement of
allowing no fallbacks in secure falcon mode.

To do this in a clean way, all the falcon mode logic for each boot media was
refactored to a corresponding *_load_image_os function whereas the regular
boot is implemented in *_load_image, this allows us to easily return early in
case the *_load_image_os function fails with secure mode enabled.

The series also introduces the new SPL_OS_BOOT_SECURE config symbol which
enables secure falcon boot flow.

The generic flow after the patch series looks as follows:

	static int spl_<bootmedia>_load_image(...) {
		if (CONFIG_IS_ENABLED(OS_BOOT)) {

			ret = spl_<bootmedia>_load_image_os(...);

			puts("Failcon mode failed\n");
			if (CONFIG_IS_ENABLED(OS_BOOT_SECURE)) {
				puts("no fallback allowed!\n");
				return ret;
			}

			puts("Falling back to U-Boot\n");
		}

		/* Regular boot flow */
	}

[1]: https://lore.kernel.org/u-boot/20250923124639.667718-1-anshuld@ti.com/
Link: https://lore.kernel.org/r/20251017193318.4124997-1-anshuld@ti.com