uboot-phytec

image: Convert fit_image_hash_set_value() to static, and rename

This function doesn't need to be exported, and with verification
we want to use it for setting the 'value' property in any node,
so rename it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>