qcom: pil: Add PIL operation to undo init_image work on pil_boot failure

Currently, if pil_boot for a subsystem fails after init_image
completes successfully, the work done during init_image is not
undone, which might not work with some pil implementations.

Add a PIL op, deinit_image() to do just that.

Change-Id: I6d219c551d752ab0ce5e2d95de15c7396379cf8c
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>