posix-timers: Cleanup restart_block usage

posix timers still use the legacy arg0-arg3 members of
restart_block. Use restart_block.nanosleep instead

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <johnstul@us.ibm.com>
Tested-by: Richard Cochran <richard.cochran@omicron.at>
LKML-Reference: <20110201134418.232288779@linutronix.de>