use msleep instead, because not in atomic

Cc: Roger Wolff <R.E.Wolff@BitWizard.nl>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>