drivers/crypto: Fix a memory leak in tc shim driver

If setting up crypto context fails enough times, the sessions will all
end up "in use" though they will not. This will lock tc shim driver
altogether and no crypto context will be possible to run on it.

Change-Id: I72346854e52294f96afc32f30ac5bfd0c368812b
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>