kcdrwd: remove unneeded flush_signals() call

kcdrwd() is a kernel thread, all signals are ignored.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>