qseecom: fix issues when processing blocked listener request

When processing blocked listener request, ptr_app's app_blocked
flag should be set to prevent it being unloaded at this time;
Besides, need to check unblock request's scm_call response result
to see if it is blocked again; and removed redundant codes.

Change-Id: I2d72a88e9e600d6b7e944ae978b9d89a7b6db242
Signed-off-by: Zhen Kong <zkong@codeaurora.org>