With SPL we want to specify the phase of the image to be loaded. Add
support for this.
This is the implementation of a FIT feature added to the spec a few
years ago and entails a small code-size increase, about 70 bytes on
Thumb2.
Signed-off-by: Simon Glass <sjg@chromium.org>
Link: https://docs.u-boot.org/en/latest/usage/fit/index.html