qseecom: Propagate qseecom_load_external_elf failure to userspace

Return value of qseecom_load_external_elf() is changed before sending
the status to user space. This patch rectify the issue and propagate
the exact failure values.

Change-Id: I00feff4fa6fc5864e1264e5ac4479eca898443ea
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>