Staging: lustre: ptlrcpc: sec: Declare local functions as static

Declare functions sptlrpc_secflags2str, sptlrpc_sec_get and
sptlrpc_svc_install_rvs_ctx as static since they are used only
in this particular file. Also remove them from corresponding
header files.

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>