efi_selftest: remove superfluous assignments

In test_hii_database_list_package_lists() 'ret' is used for the return code
of EFI API calls and 'result' for the return value of the function. Writing
EFI_ST_FAILURE to ret is superfluous.

Fixes: 4c4fb10d ("efi_selftest: add HII database protocols test")
Fixes: ee3c8ba8 ("efi_selftest: fix memory allocation in HII tests")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>