selftest/s4: remove illegal function signature

selftest/s4: remove illegal function signature

The character ':' has no meaning in function signatures. Perhaps ';' was
intended, which would have marked the later arguments as optional --
which is the default with no signature. All callers always provide all
the arguments anyway.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>