qseecom: Fix error handling path in receive_req()

This patch fixes the error handling path in receive_req() function
called from userspace. Issue seen if user is calling the receive_req
function without calling the listener registration. qseecom_find_svc()
should return NULL if there are no services found.

Change-Id: Id51d8f48d7266b5acbc845f7b9ac0068d16b1ede
CRs-fixed: 496927
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>
qseecom: Fix QSEECOM_IOCTL_UNLOAD_EXTERNAL_ELF_REQ kernel crash

Fixes the kernel crash occuring with IOCTL_UNLOAD_EXTERNAL_ELF_REQ
ioctl by adding unavailable client type to qseecom_client_handle_type
enum, which is required in the driver during qseecom_release().

Change-Id: I73b817255149ffc4a808852feb2954a0ba3c317f
CRs-fixed: 508253
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>