mm: convert sprintf_symbol to %pS

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Jiri Kosina <trivial@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>