We try to enforce it by using -Wstrict-prototypes, but apparently they
sometimes get through.  Introduced by 4eec42f3 ("watchdog: Change
the default timeout and configure nmi watchdog period based").
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>