smcinvoke : file private data validation, which is sent by userspace

a validation added to check  whether retrieved struct smcinvoke_file_data
inside the function get_server_id belongs to g_smcinvoke_fops or not.

Change-Id: If949889a764775200650a8d0b744359c0611b576
Signed-off-by: Pavan Bobba <quic_pav@quicinc.com>