efi_loader: improve error handling in try_load_entry()

The image is not unloaded if a security violation occurs.

If efi_set_load_options() fails, we do not free the memory allocated for
the optional data. We do not unload the image.

* Unload the image if a security violation occurs.
* Free load_options if efi_set_load_options() fails.
* Unload the image if efi_set_load_options() fails.

Fixes: 53f6a5aa ("efi_loader: Replace config option for initrd loading")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>