autofs4: clean up uaotfs use of debug/info/warning printouts

Use 'pr_debug()' for DPRINTK, which will do the proper type checking on
the arguments (without generating code) even when DEBUG isn't #defined.

Also, use the standard __VA_ARGS__ for the macros, and stop the
pointless abuse of 'do { xyz } while (0)' when the macro is already a
perfectly well-formed single statement.

Reported-by: David Howells <dhowells@redhat.com>
Suggested-by: Joe Perches <joe@perches.com>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>