store __setup_str_* in a more compact way

__setup_str_* are referenced only during boot, hence there's no need to
waste image space for aligning these strings (with the aim of improving
performance).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>