net: ipc_router: fix leak of kernel memory to userspace

The service info structure is allocated with uninitialized memory for the
max number of services and returns the complete structure to the usersapce
resulting in the information leak if lookup operation finds less number of
services than the requested number.

Check the minimum of requested and available services and copy the minimum
information to the user-space.

CRs-Fixed: 965934
Change-Id: Ic97f875855fdc6440c1db1d8d0338ee8b03a9d0a
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>