dynamic_debug: consolidate DEFINE_DYNAMIC_DEBUG_METADATA definitions

Instead of defining DEFINE_DYNAMIC_DEBUG_METADATA in terms of a helper
DEFINE_DYNAMIC_DEBUG_METADATA_KEY, that needs another helper dd_key_init
to be properly defined, just make the various #ifdef branches define a
_DPRINTK_KEY_INIT that can be used directly, similar to
_DPRINTK_FLAGS_DEFAULT.

Link: http://lkml.kernel.org/r/20190212214150.4807-5-linux@rasmusvillemoes.dk


Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>