client_state: Call validate_column_family() with database arg
client_state: Call validate_column_family() with database arg

The previous patch brought the databse reference arg. And since
the currently called validate_column_family() overload _just_
gets the database from global proxy, it's better to shortcut.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla